The Hidden Forest

I am curious if it is possible to make single target heals if cast with an NPC on target to cast on the person casting the spell? Instead of trying to cast on the NPC and causing a "will not hold" message. This would be really cool for say a paladin tanking to single target heal themselves without having to constantly swap targets which can get hectic on encounters with multiple NPCs etc.

Something like this was done w/ TGB recently so I was wondering if it was possible?

there was a discussion with this kind of spells on the class balance discussion.
I'm personnaly against it , where is the fun if you only have to push 1 bouton ?