With my current setup I don't need the 5 buttons (4 in my case) for failover - it's automatic.
/target [target=Shaboôm, nodead]; [target=Shabôom, nodead]; [target=Shabôôm, nodead]; [target=Shàboom, nodead];
/follow
that's my failover AND follow macro. Add in the attack macros that a: just cast if it's an enemy or b: target the targets target if the current target is helpful, and it's a 1 button mash failover.