OK, as promised I've compiled a very detailed guide for bracket fabrication and installation of the brackets and steps. It has lots of pictures and a full set of prints, but that unfortunately makes it a huge document (96MB). So, I've hosted it on my personal Google Drive, but made it publicly available via this link:
Bracket Fabrication and Install Guide for Amp Research Powersteps (1st Gen K5)
I'll also attach just the prints to a later post here.
Hopefully this helps someone out there!