How do you make an ability not show up in the UI?

Basically what I want to do is give a unit an ability, but not have a button show up for the ability. Is it possible to do that with any ability?

Disable it at Map Init. and then enable it for a short moment to use the spell or whatever then disable it again.

E- Ability is bein cast
C- Spell = whatever
A-
Enable whatever
Run whatever<gen>
Disable whatever