I've stated this in other posts, but using a hardware device like a Nostromo N52 or G15 Logitech Keyboard or the X-Keys device (which I don't know much about) can help you without having to use the Autohotkey program.

These devices basically can be programmed to perform the ALT-Tabbing for you to make it a little simpler. One keypress can ALT-Tab to the second character, send the keystrokes you want, and then ALT-Tab back to your main. There is of course a delay associated while all this occurs, but its much better than trying to manually ALT-Tab back and forth.

The best way is to have separate computers of course but if you are going to dual-box on just one PC these devices can help.