That's the first I've seen one, but that's a darn nice seat!
Cheap too!
Installing it shouldn't be too tough, set it where you like it, mark the holes and drill.
You may want to also look into adding a piece of steel strapping beneath the tub for some re-inforcement. I'd also add a rubber washer between the foot of the seat, and the tub to help prevent cracking.
Good luck, and take some pics!