There are a couple of small mounts on the aluminium bracket that connects the topdeck to the shocktower (JC1111), the bar mounts between them and the back of the front tower
http://www.m-k-racing.com/product_in...oducts_id=4260
(The slots at the bottom)
I seem to remember last time I tried one a B4 rear rollbar pretty muchy fits straight on.