test it. You won't love it, but it will get the job done with some patience. The /targetparty command cycles through your party just like you TAB target enemy mobs. So you'd have to hit the button once, wait for the GCD, then hit it again, wait for the GCD, then hit it again. PLUS, I believe all your party members have to be on your screen. (not confirmed since i stopped using this macro a long time ago, but I'm pretty sure it was one of the reasons I stopped using it.)

I use SmartBuff . It hasn't been updated for 2.4, however from the character selection screen click on the addons option (on the bottom left of your screen) and then toggle Load out of date addons. You can play around with the settings. Word of warning, it's a spectacular addon and if it ever stops working you'll be forced to go back to PITA buffing.