If you talking about what i think you are just mouse over the skill it'll tell you the cool down there's not much thinking or complexity to it mouse over and learn to read.
Oh really? wow! I didn't know you were able to read the cooldown! THANKS DUDE!
....
Now, if you're done being a douche, try thinking about WHY I might be asking if anyone knows a function for it. Though I think that'll be too hard for you to figure out, so i'll tell you. I simply want to condense 3 action bar slots down into 1. I use every bar slot available already, so don't have the room to be adding ISS's to it just to check cooldown. Now for the reason - I play rogue and have Kanches Rend hotkey'ed on Action bar. I wanted to replace that hotkey with a macro that casts Kanches, but if it's on cd use Phantom Stab instead, and if neither of those cast, tell me in chat what their cooldowns are.
As far as I know, there is no way to get the remaining cd time for ISS, without going through action bars.
Thanks for an actual valid response, somebody could learn something from you apparently... And darn, guess I'll have to go with simply casting both at the same time. I know that works but isn't quite what I was looking for.