IMO you should go full mastery demo w/ 15% hit cap (bosses are 93).
I have done 9/9 on two different Warlocks and in both cases went mainly as Demo and then offspec was Affliction. Since most of the instances are about trash that has a very high burst requirement on it, Demo offers that for the group. For cases where you will want the single target dmg that Aff offers you have that spec available to you as well (there are times/cases where you will have full fury for a boss fight and demo will just be better but other times where you will have none and need the upfront damage Aff gives).
Talent wise as Demo I had Harvest Life/Shadowfury/Sac Pact/Burning Rush (or Blood Fear depending if I was CCing with Fear glyph)/GoServ (honestly I was a little lazy and stayed GoSup for most of it and both groups I ran with had enough AoE without GoServ, but both are viable options)/swapped between MF and KJC.
As Aff I generally had SL/SF/DB/BR (or BF)/GoSac/KJC - nothing really to change here.
IMO this is the best way to spec for each instance;
Specs: Demo + Aff combo, mostly Aff
- Be Demo for the first pull/boss - since the first pull is the whole hallway you are there for a few things; knockbacks w/ Carrion Swarm, Shadowfury - AoE CoE + aoe. Use Infernal on this pull as a stun/CC + dmg.
- Immediately after the floor falls and you start going down that 2nd hallway downstairs, leap and respec to aff. The reason you do this is; a) you gain some easy distance, b) you will likely be using an invis pot before/after that first mob and you have to have your pet dismissed (it doesnt gain invis and cant jump over the ledge with you), c) multidotting the adds for 2nd boss puts you at an advantage since you will be swapping to whatever add gets the reckless buff (takes increased dmg)
- stay affliction for rest of the instance, the pulls aren't large enough to warrant being Demo and you don't have time between 2nd boss and the last set of pulls to respec
Gate of the Setting Sun:
Specs: Demo + Aff combo, mostly Aff
- First pull/boss; demo again is going to be what you want to do as the first hall there is again a massive aoe pack and having Sac Pact to save your tushy from being toasted by bombs is nice - you should be able to have near full (or full) fury for the boss and just burn him down
- After the boss, leap as far as you can and respec to aff...dot the mobs and keep them dotted as you kite them away to the next pack, it was my "job" to kill them before they crossed the bridge.
- Stay affliction for the remainder of the instance, 2nd boss you should be DPSing as much as possible on the boss without sitting in fire (should be nearly always hitting the boss) -- trash up to 3rd boss and 3rd boss are smaller packs that aff still does well on and then last boss is pure single target and your pet can't attack the weak spot
Siege of Niuzao Temple:
- You are going to be Affliction for this entire instance; there are no large aoe packs and every boss is single target required DPS
- First few trash packs are only pulls of 4 and then the little oozes that explode for ramping dmg every one you kill so you want to kill them one at a time, first boss is DPS monkey
- Second boss, again you will stay aff and just multidot the adds while the tank has them in the puddle, kill the guy that gets sent over and hit the gong as many times as you can to gain time from the RP beforehand. Keep your portal up top so you can port up after a spinning strike thing and put another bomb down (make sure you jump back down after)
- Third boss there is some AoE component to the fight but the bombs will take care of you, liberal use of them on those large trash packs and the boss is HIGHLY recommended
- Last boss you will want to sac a felpup for and have your port on one end of the bridge and interrupt ASAP; the boss cannot be casting for more than 1s if possible - leave early going the other way to interrupt (you will be able to get both).
You will be Demo the entire instance mostly because the whole instance is AoE.
First pull + boss, just a pure aoe fest - kill the sprites in the air that are empowering the monkeys with fire or they will crap on your tank - aoe all the 40 mobs, use carrion swarm/stuns/infernal. For the boss I would suggest for you to NOT be on barrel duty; your pet disappears and you can't be in Meta form. IMO let the other 2 DPS and healer do barrels, 3 people doing them should be plenty.
On the way to the second boss you will want to kill the hammer bunnies as you go (let your pet tank cuz they do a lot of damage) and pick up the hammers, kill mobs until boss comes out then kill boss. you can cheese some fury on this fight with hellfire on the adds that come down for better/bursty damage.
Rest of the instance is pretty much self explanatory; aoe mobs, kill boss. A trick about the boss is you can have your pet stand in front of one of the healing adds and soak up the healing 100% of the time. You basically gain an extra person to soak the healing beams.
Temple of the Jade Serpent:
Specs: Demo+Aff (half/half)
First boss you go to should be to the left (wise mari) and you will want to be Demo for this pull/boss. the AoE for killing all the small adds + the bigger elementals is going to be essential. You are able to stand in a sweet spot and just get knocked back up against the wall instead of running around the circle and just heal through the damage.
On the way over to the other side of the instance for the 2nd boss dismiss your pet (this is where most groups invis pot all the way over to the bridge) - start resummoning your pet once you get to the top of the bridge - aoe the trash (it silences so you need as must burst aoe as you can get) then keep both your dots on the boss (you swap often enough that you will never have corruption fall after the initial cast)
Get over to the trash after that boss and swap to affliction - multidot the bigger adds and SB:Seed to do moderate AoE damage to the smaller silencing adds. Boss is easy and single target straightforward.
Last boss is another single target burn with the 5 adds that spawn (you can drain them for full shards so you will never be starving for shards).
Specs: Demo(first pull)+Aff(remaining)
First pull you will be Demo as there are a TON of adds and you need to AoE them down, bursty/sustained (use all your CDs, Imps included as you will be swapping to aff as soon as you drop combat from that pull).
First boss you will be Affliction and you will stay Aff the remainder of the instance, moderate AoE pulls that multidotting is more than sufficient for and the remaining bosses are all single target fights with no real opportunity to go in with decent fury. Pretty basic instance when it comes to DPSing.
For this instance you will be Demo from start to finish because there are many many many maaaaaaaaaaaaaaany AoE pulls and the extra CD w/ Sac Pact saved me more times than I can even think.
First boss; don't stand under books. They hurt....a lot.
Second boss; either have someone with the WoW script or use this WA* to see which is the right add so you kill it in one shot and not prolong the fight and cause damage that you don't need to cause.
Third boss; killing the initiates as Aff is kinda lame but just UA/Corruption when you don't have shards for SB:SS - fel flame the image of the 3rd boss to get rid of it ASAP.
Rest of the instance is the same as normal but more damage - the only precaution I would give is for last boss where you are basically required to kill the voidzones that spawn before they drag you to them (causes a ton of that debuff to build up + it slows you).
*3D model WA:
This is another all Demo instance; the pulls are loud and large and you will need the damage you get from Demo to overcome it. Most of the bosses you will go in with full fury making it extremely lucrative not change specs.
Nothing really special to do in this instance except do max AoE DPS.
I have done this instance as either Aff only, Demo only and a mix so really do what your group will need the most. The groups I ran with had the "easiest" time when I was Aff the entire instance because there are not many large AoE packs where DoTs aren't going to be a hindrance to the groups DPS and in some cases will be beneficial.
**This is not to say that Destro is bad or is the wrong spec for challenge modes but this is to say that you can do it as either and any spec and this was just MY experience and yours may be different. There are other tips I could give if you had specific questions but I think I covered most of it. Things that could change what you are able to do when will depend on where your group wants to do use Invis pots (this will determine if/when you can use DPS potions, when you have to dismiss your pet, etc).