Since you can use moonfire in bear form, you can't have a macro that automatically uses both moonfire and mangle. If you just place them in, it will only ever use the first one listed, and if you use /castsequence, it will use one, then the second one, then get stuck on the first one until it comes off of cooldown. If you're okay with constantly casting moonfire-mangle-moonfire-mangle, here's your macro:
Code:
#showtooltip
/cast [help] Rejuvenation;
/castsequence [stance:1,harm] reset=combat/target Moonfire, Mangle
This will cast rejuvenation on friendly targets and cycle moonfire and mangle. The cycle resets when combat ends or you switch targets, so moonfire will always be the first spell used. Here's another option where you can use a modifier key:
Code:
#showtooltip
/cast [help] Rejuvenation; [mod:shift,harm] Moonfire; [stance:1,harm] Mangle
This will let you spam mangle, but holding shift casts moonfire.
As a note, the bear form part of the macro is [stance:1]. 2 is cat, 3 is travel, and 4 is moonkin.