…maybe not “forever”, though, but it did (Eventually) did good.

I moved the installation to “c:\strawberry” as dictated by the manpage, and made sure to set the path variables to the correct places. (Also, I’ve added a path variable to MinGW’s bin folder, just to be on the safe side). Then, I tried installing the modules that were acting up originally, which was mostly successful, apart from Tk. Installing it turned out to be a bit of an issue.

A quick search later, and I got some general complains, and even more general solutions, until I hit pay dirt (http://rt.cpan.org/Public/Bug/Display.html?id=13923):

I built Tk via the strawberry perl distribution today. I also had the
“missing file”. The file was not missing, but rather there appears to
be a relative path in Xlib.h at line 1206

#include "../pTk/tkIntXlibDecls.h"

but xlib.h is at C:\Tk-804.027\pTk\mTk\xlib\X11
and there is not pTk dir up one directory.
if you create a pTk dir at C:\Tk-804.027\pTk\mTk\xlib\pTk
and put tkIntXlibDecls.h and lang.h there the build will complete just
fine.

Really weird stuff, but it actually worked. After performing the movement, and re-running Makefile.PL, I managed to build, test, and install Tk, which means I now have, hopefully, all I need.