This video
http://ca.youtube.com/watch?v=xgTJcm...e=channel_page shows our mecanum robot rolling around with AM Mecanums and BB trannies. Unfortunately, I don't have a close-up of the wheels mounts.
Basically we turned our own hub, and cut a keyway to match the shaft on the BB tranny shaft. We mounted the BB tranny to the frame, and built an outboard bearing block to support the outboard end of the axle. The mecanum wheel was bolted to the hub, slipped on to the axle, a set screw was tightened to hold it in place, then the outboard bearing block was placed on the end of the axle and the whole assembly was put in place and bolted to the frame.
Jason