SOLVED: Here's what works. It's not even hard.

If pp is already installed, then remove it with cpanm --uninstall pp

Find the directory C:\Strawberry\cpan\build\PAR-Packer-1.037-0 (or equivalent) and delete it completely.

Re-get PP from plain Jane, regular CPAN like so get pp but do NOT make or anything else.

Find the directory C:\Strawberry\cpan\build\PAR-Packer-1.037-0\myldr\winres (or equivalent) which you had just now got

Delete from that dir the file pp.ico and replace it with your own *.ico file naming it as the new pp.ico

Now open a CLI (aka DOS) window into the path C:\Strawberry\cpan\build\PAR-Packer-1.037-0 (or equivalent) and do...

perl Makefile.PL

Then dmake Makefile

Then dmake test

Then dmake install

And now you are done. Henceforth a call to pp will have your own *.ico already built in. Sorry, no changing back. Start over from scratch if you want to do that.

And if for you, as it does for me, a call to pp in the regular way still dies with errors, next go hunting right here at PerlMonks for something called ppsimple.pl and use that instead. This is what I have had to do. A few hoops to jump through but at last now it works.