I'm just tri-boxing shaman's at the moment. just hit level 17 yesterday so not particularly high yet. As for Healing macros, I currently have keys bound to F1, F2, F3 for toon1, toon2, toon3 to heal their focus. This means I can have only one of the shamans healing one of the others. I also have Shift+1, Shift+2, Shift+3 to make all shaman's heal toon1, toon2, toon3 etc.

Attacking wise I use a simple /assist toon1 macro.

I'm sure healing will majorly change once chain heal arrives, so i'm sure someone else will be able to assist better than me.

My current best achievement would be managing to trio the first boss in RFC at lvl 16. I was quite happy with that (even if a Pat i'd missed did come and finish me off when he died. lol. ooom ftl)