I'm currently working with a friend that plans to replace his one piece crank with a BBS02. The main issue is that the bottom bracket shell diameter is much larger than the standard 3 piece crank shell that the BBS02 is sized for. There are standard adapters available, but they have the hole through the middle centered and that doesn't leave enough clearance for the BBS02 to slide in.
My friend plans to have a couple of fairly thick shouldered adapters made at a local machine shop with the correct size holes for the BBS02 drilled near the edge instead of centered. There are other potential solutions, search on "eccentric bottom bracket American to English".
It will probably be a while until I can report on the success of his project. He lives an hour and a half away, by car, and I will be taking my spare BBS02 over to him sometime next week so that he can get the measurements he needs for making the adapters.