Assuming I can find that older compiler on MSDN subscription ...

I think you can get it here. Though, I tkink BrowserUk found that gets you an updated version that doesn't have (and doesn't need) bufferoverflowU.lib. Iff it *is* that updated version, you then need to remove '-lbufferovewrflowU' from the 'libs' and 'perllibs' entries in Perl/lib/CORE/Config_heavy.pl.

To set up the necessary environment variables, I run (on Vista64, btw): C:\full\path\to\SetEnv.cmd /XP64 /RETAIL

When that's done everything should simply work (using the existing %Config values). However, I don't know about CPAN.pm - I don't use it very often and have no interest in even thinking about any problems it presents. (I generally just install modules the old-fashioned manual way.)

Cheers,
Rob