Oct 22nd 2010 11:49AM Hal -
I'm not sure how the spell works, since I don't play a priest, but just because it's a proc off Chakra doesn't mean it's hard to Macro.
Open a macro and shift click the spell in your spellbook, or you can type /cast Holy Word: Sanctuary in, but shift clicking ensures the name is put in correctly. Then hit enter, and type /ra Now Casting Holy Word: Sanctuary! Go to the light children! (or whatever phrase suits you..)
If you have raid assist or lead, you can do /rw and get the nice on screen pop-up. You can also do a /p instead of /ra for those 5 mans. Or if you have an chat addon that supports "smart group" chat, you can probably do a /group (or whatever the addon supports) and have it go where it needs to.
If you REALLY wanna cover you bases, do a /ra, /p and /rw and just know that you'll be spamtastic.