Yes, I got Tk to work with perl 5.8.1 on macosx 10.3 panther; but first, I had to download the complete source package for X11R6, because the make stage for Tk needs the header files (*.h) from the X11 source distro (which is not part the standard macosx manifest).

I think you'll find what you need here: http://www.xfree86.org/downloads.html -- don't let the "86" fool you: the part that matters is straight unix, without architecture issues.

It's been a while (nearly a year) since I did it, and my memory for details is fuzzy, but once you have the /usr/X11R6/include path on your mac, the Perl/Tk installation should proceed just fine. You don't need to build all of X11R6 from sources, you just need the *.h files to build Tk.