Post by Queggy
I believe what you are looking for is this
Post by Strandvaskeren
First of, the forums on http://www.dual-boxing.com/
has a wealth of info on playing multiple accounts simultaneously.
Secondly, have a look at a program like http://www.solidice.com/keyclone/
it cost $20 and transmits your keypresses from one copy of wow to another (or several others). Blizzard has stated several times on their forums that they are okay with us using Keyclone. It doesn't matter if you use 1 machine running a couple of wows or a couple of machines running 1 wow each.
Basically, with keyclone everytime you press 4 on your main computer, keyclone press 4 for you on the laptop. Both your chars will then do whatever spell/move you assigned to the 4-button.
As for macros you mainly need 2:
First macro is a follow macro for your slave. At some point it WILL lose follow mode. Lets say you bind F12 to the follow macro on your slave and F12 is bound to nothing on your main. If for some reason a lamp post jumps in front of your slave and it stops following you, you just run back in range and press F12 and your slave will do /follow exmortis
Second macro is a target macro. You pick a target with your main, then press T (or whatever key you prefer). On your main T is unbound and does nothing. On your slave T is bound to a macro doing /assist exmortis. Now both your chars have picked the same target and are ready to fire..
You then press 1 which starts casting a shadowbolt on your warlock main and a frostbolt on your mage slave, and a moment later the mob is hit by a shadowbolt and frostbolt..
It takes a bit of fiddling in the beginning but you should be up and running in an hour or so.. You could start with using just your main account and a trial account for a couple of days, just to see if it's something for you or it drives you nuts before you fork out the money for an extra account.
As for playable, it's like playing with a really retarded friend on follow, it requires patience but it's doable and kinda fun if you like the challenge..