I have dabbled in retail a few times with 2 toons. I use Hotkeynet and for the slave toon i have follow and one spell (sunfire) for tagging running through it. I use 1 and a mouse key for these and I make sure those keys do nothing on my main toon, and I wait a second or so to press the spells on the slave to make sure they don't cast or act at the same time. I got caught with a vehicle quest tho and casted both at the same time, but I caught myself real quick. Anything besides tagging really I manually tab over and control each character separately. I try to make it look like I'm not running software as best as I can. Of course now with TBC out and mobs taking forever to kill on 1 toon, I'm getting the itch to try this in classic. I only have done this method for 2 5 hour play sessions tho.