Alien::Imager has escaped onto my Perl repository. With it, I can (almost) automatically install Imager with JPEG and PNG support on Win32, provided a suitable C environment is available. A pending patch to CPAN allowing a parameter to the recompile command will then recompile Imager with the added libraries.
I could not get Giflib to compile nicely on Windows, and I could not get Tifflib to play nice too, so these two are missing from the Imager build.
Configuring Imager was greatly simplified by Imager allowwing environment variables for all of the relevant parameters to Makefile.PL. If your module requires configuration during the Makefile.PL or build phase, please consider supporting environment variables so that external scripts can set up the environment and then install your script through CPAN.