Well, it seems I found a C program (GPL) that can print a PostScript
file in a printer from Windows:
Printing PostScript Files from Microsoft Windows
http://cybertiggyr.com/gene/psw/
But I didn't test it.
I guess that can work in some circumstances, but it bypasses the
printer drivers. Couldn't that lead to problems for the printer drivers?
Yes, it bypasses the printer driver, what kind of problem?
Couldn't anyone who has Windows test this program to see if fixes the
problem (or part of it)?
It could be a start point for a solution.