Most of the build scripts for extended are still in the pd-l2ork git. It is a relatively simple matter of making sure:

1) tkpath builds cleanly on Windows (which it should)
2) tkdnd builds ok on Windows (which it should)
3) Windows has xapian and tkxapian libraries (which it should)
4) and then hunting any stray idiosyncrasies within the pd-l2ork's tk scripts (there should no more than a few linked to the startup behavior).

Basically, it is a matter of someone spending a bit of time hunting these down and refining scripts as necessary to make everything buildable in as automatic of a way as possible (e.g. on Linux pd-l2ork uses a single command to build the entire monolithic deb or tarball installer).

HTH