Q. Is ITV2 available with a Sky subscription in the RoI?
A. Yes.
It's on the Services Menu->Other Channels. It has to be tuned in manually.
There is an excellent explanation of how to do this for ITV2 and many other UK terrestrial channels on [broken link removed].
It can also be tuned in on any other digital box, i.e. you don't necessarily have to have to have a Sky package.