Mouseover Cast on Frames Only?

Is there a way to get mouseover casts that only targets a frame? I used to have this working with Cell, but i’m trying to get it done without it.

Example: I have Warrior selected, and I mouse over Mage’s party frame. I press holy shock. It should target the mage, because they are moused over. But right now when I have hover cast on, if my mouse is over the mage’s model, not unit frame, I want it to cast on my target, not their model. Is there a way to do this?

Not natively. The way to do it natty is to right click so your cursor disappears.