Heres the pics, started by taking the standard steering wheel off as normal(make sure your wheels are straight before you start), then put the boss up against the hub and see roughly where you have to cut, with mine it was 45 degree angles froom the base of the hole where the small stalk comes through.
I then cut a metal cutter guy to just cut through the metal, cut the top piece straight off!!
Ithen put the boss against the hub, made sure it fit ok, slide the rubber cover over the boss, making sure you get it round the base of the boss(it is a tight fit) then continued to fit steering wheel.
Once the boss and wheel is fitted you cannot hardly see where is cut unless your looking for it.
Walla, steering wheel!!
Also, just incase some members didnt know, the momo boss for the supra also fits the mk2 MR2 momo part 7728. I searched for a mr2 momo boss on ebay and got one for £15.