You can probably register them all on load.
I just tested it, it doesn't work like that. You get a ERROR_PROC_NOT_FOUND when calling CreateWindow, because it tries to call RegisterClassNameW.
Finally managed to create an own side-by-side assembly, I attached it. It consists of one executable and one dll, compiled and created with codeblocks under windows 7, also tested in windows 7. I included pre-compiled binaries, but you'll need to run it from the explorer not codeblocks, because the paths must be right.
Do we want this included into wine in some way? I hope this is good enough (and that it compiles on your system).
Regards, Fabian Maurer