Setting up round robin processing of the keystrokes works well enough in eq2.

1 keystroke per game action is not that hard to work with, the ability queuing system allows each keystroke to cast one spell abilities/keystroke and queue the next.

You want both your healers to cast a heal on tank just have to hit the heal key twice instead of once. First ketstroke throws a heal from healer 1 and second keystroke throws a heal from healer 2.

This still fits within their guidelines and I have managed to 6 box almost all SF instances.