depending how un-lazy you are, you may just use prayer of healing for spot heals. That's what i've done, and so far its worked pretty well. If one of the alts are getting hit hard enough that it warrants more healing than Prayer of Healing can cover, i have another button (3) that /assists main, and /casts heal, on 4 of my slaves (main does not cast heal, becuase when he is casting he can't dodge/parry/block). This way the person who is taking the major heat gets a flash type heal (flash heal on priest, lesser healing wave on shamans) from 4 sources, totaling about 5k healing in 1.5 seconds. Disadvantage of this is that my master (pally tank) has to re-target off of the mob he was tanking, wait 1 second for the slaves to "get" which target he has, and then hit the heal button. A bit more of a delay than is optimal, but still better than having the slave die =)