I thought about mentioning that, but then realised that even if you could get your hands on the very old versions of the libgd sources, you'd probably need a very old version of Perl also to make the whole thing hang together.

I did build GD from source once, but it was a pain to do, took ages to gather all the requisite bits together, and was genraly a PITA. Along the way I patched a couple of bugs, but then installed a later version of perl and screwed things up. After that I went back to using PPM to install it.