And now I have to move to a new platform to test it all again. The setup script should be close to what I need, but, of course the stuff I typed at the command line needs to be rewritten on the new machine...
Are you asking about building your build scripts? I don't see why build scripts can't be treated as another package. The Unix way to handle cross-platform builds is configure (the docs even say there is Win32 support). The Perlish way is Module::Build or MakeMaker.
If you don't want to carry Perl around, it sounds like you may just want a variant of make clean that only impacts the 'build scripts', whatever they are. Makefiles are not Perl specific, all the platforms you mention should have a version of make (nmake for windows).
Or, maybe I've missed your point entirely.
You said you wanted to be around when I made a mistake; well, this could be it, sweetheart.