try this build:
http://www.worldofwarcraft.com/info/classes/warlock/talents.html?2502220502231105512010040000000000000000000505000010000000000000
at level 70 it should look like this:
http://www.worldofwarcraft.com/info/classes/warlock/talents.html?3502220512231105512010250000000000000000000505000010000000000000
instead of your Felguard you are have to tank now, which is perfectly viable with the talent Fel Concentration.
Basically you DoT up a mob or two and draintank them, which means they aggro you and you keep your Hitpoints up with Drain Life. Once you get confident you can easily do 2-3+ mobs at once without with just losing a few percent life and mana and you end up with almost no downtime.
Remeber to Dark Pact your Imp, which is set to passive, and remember to drain soul (with the improved drain soul you will regain 15% of your maximum mana if drain soul is on the mob while it dies)
Edited, Mar 7th 2008 1:14pm by Oakenwrath