I'm making a note to myself to post my Destruction lock's rotation when I can get back to my PC. I thought the rotation was fairly simple; he is basically a fire mage now. You'll just have to be aware that locks need to life tap (convert life->mana) every once in a while to maintain mana but their rotation will replace the health shortly after (Soul Leech talent), or have a pet out and just steal from them (which means they shouldn't attack or there might not be anything to steal). Plus, the Improved Soul Leech talent will occasionally proc a little mana regen for the whole group/raid.

I tried Affliction, which was great on a boss, but pretty much required a separate macro for trash mobs. Ideally, you want to Seed of Corruption most trash right away, but that's such a nuisance while boxing. Probably better just doing Shadowbolt spam on trash. I should still have his boss macro saved if you're interested in that route. Affliction will also require you to life tap, but has Haunt as it's 51 point talent which is a DoT, DoT damage booster, and heals you when it expires on the target (the visual effects of Haunt are kinda cool too).

I simply didn't try Demonology, as I didn't want to have to mess with pets and worry about maintaining enough shards (i.e. more micromanagement). Greythan can probably give better tips here than I can.