You'll need some ISO keycaps ofcourse, but all you need to do is bolt mod it, and move a few springs/hammers over to the proper locations when it's open.
I think that's all there is to it, cause IBM saved money by going with an ANSI/ISO cotnroller and membrane, if I recall correctly.
If you need more info about the bolt mod, just ask, and I (Or someone else) can fill you in.