mozilla/addon-sdk — pull request #246 by KWierso (2011-10-10 23:38:25+00:00)
Title: Look in HKCU if Python is not found in HKLM on Windows (bug 684136)

I think this works. I don't have Python installed "just for me", so I can't really test that it finds it in HKCU, but this looks like it would work.