As it turns out, I successfully tanked Ji'kun, Durumu and Primordius on my low geared Paladin in an alt run as well, this week. The difference is that our opinion of 'low geared' is a little different; my equipped ilvl was 478 at the time. My current sword, hands, belt, and both trinkets were all acquired after that kill. I had blue items in all those slots on Sunday (plus the Darkmoon stam trinket, which I will swap back in again this weekend). Dark Animus trash was no problem either. We tried Dark Animus himself, but our other tank was having problems surviving the mini-golems, so I switched to my geared Druid just to take the stress off of the group.
Our logger switched back to his main after this wipe and forgot to continue logging, but you can see in my character sheet that we did get the kills (though we subbed out some toons that were doing bad DPS).
http://us.battle.net/wow/en/characte...owell/advanced
http://worldoflogs.com/reports/rt-bf...?s=3654&e=4077
At this level of gear, the main concern is obviously living through things like Talon Rake and Serious Wound. That's why I stacked the hell out of Stamina and hard-capped Hit/Exp before adding any Haste at all. My DPS was terrible, of course, but the healers had very little trouble with me. I took less damage than my Druid did last week on our Dududu farm kill, and did about the same amount of self-healing - even with nearly a full 50 ilvl difference in gear.
Besides Sacred Shield, of course (and be sure to refresh it with high Vengeance, whenever a GCD is available), the thing that helped me the most was taking Holy Avenger. Since my damage is equally bad with or without it, I just save it for when I'm most vulnerable and can benefit from chaining multiple SotR buffs together. It's really fantastic when it comes to healer-pressure moments. If I think I could be at imminent risk of death, I use Ardent Defender as first priority, and Lay on Hands/Divine Shield only if that's on cooldown.