You'll also want to install at least the JPEG and PNG libraries as well, if you want GD to be of any use.
There's a whole lot of hoop-jumping to get this done, but the most straight-forward instructions I've found for doing this is at
http://www.stepwise.com/Articles/Wor...-06-12.01.html
When you're compiling PHP (I assume it will be 4.3.3 or 4.3.4, right?) make sure you set the following parameters:
--with-gd \
--with-zlib=/usr \
--with-jpeg-dir=/usr \
--with-png-dir=/usr \
That will force PHP to compile with it's built-in GD library (which is a GOOD thing - it's premade to work without any fuss) as well as including support for your new JPEG and PNG libraries.
I've also worked out (after much trial and error) how to include FreeType without using Fink, so drop me a line if you're interested.