Christoph told me that they already tried to use cmlib to generate the hives and it didn't work, but I have no detailed information.
Not exactly cmlib, because we're not very experienced with C. We have tinkered a bit with pyhive and got it running on x86 with help from IRC, but as we essentially don't know anything about Windows internals, we gave up on figuring out why the resulting hives wouldn't load in Windows.