Only Cast Proc ?

under Feral macro i can see

“/cast [@focus,combat,noharm][@player,combat]Healing Touch”,

When its in a macro it only cast healing touch when it proc.

Is there a way to make the same thing with Moonfire in Guardian Spec ?
Talent: Galacric Guardian gives proc where moonfire generates 15 rage.

no real way to do that but you could add a modifier key to hold when it procs