I keep Pommel Strike on the second row, below Force Sweep. That way, when it will work on a mob, there is very little delay in me hitting it. I have noticed that PS is able to be used when something is held in Stasis. Maybe if you are with another person that has the same ability? It also works on droids that have been 'disabled'.
Opportune Strike...I've never even seen it light up so I could use it. I just removed it from my bars and never thought about it again.