I thought I read the rules in one of the books for Ork Wierd Boys but can't seem to find them again. Are they in one of the Rogue Trader books or did I see them in one of the other games or totally dream it up?

The Ork psyker is scheduled to come out in the Navis Primer - the next planned release for Rogue Trader. I don't believe that there is a set release date yet.

Ryath said:

There's an Ork Weirdboy in Only War as an enemy.
If you want to house rule them here's a bit of advice taken more or less directly from OW.
Ork Psykers have their own (hilarious) perils of da waaagh and they get strongr the more orks are around.