You're trying to do this the hard way. Honestly, multiboxers have one HUGE strength - we can earn money SUPER fast doing dailies.

Its just painful to jump into heroics when you're way undergeared. Do dailies for a few days, make thousands of gold, then buy yourself a HUGE leap in gear all in one sitting.

When I hit 80, I finished all my storm peaks and icecrown quests in a few days and had like 20k gold. I spent it all in 1 day buying all sorts of BoE epics, gems, enchants, etc, and walked into my first heroic about a week after hitting 80 with something like 1600+ sp on my shamans and my tank was uncrittable with ~23k hp and 19% dodge and 15% parry.

This is far FAR less painful then trying to master heroics while controlling all 5 characters and undergeared to boot.