In general, the rule has always been that makepanda will build for the version of Python that you’re running it with. So, if you want to build for 32-bits Python, you’ll need to run makepanda.py with a 32-bits copy of Python; if it is a universal copy, you’ll need to force it into 32-bits mode.
There is 64-bit OS X and Cocoa support on the CVS trunk, so if you check out from the CVS repository, you should be able to produce a Cocoa build if you prefer.
If you wish to make a 64-bit build, you’ll need new thirdparty packages; I built a few, but not all are present.
rdb.name/thirdparty_mac_x86_64.tar.bz2
If you wish to make a 32-bit build with the latest CVS trunk, you can use the “–arch i386” flag, which was recently added to makepanda. You can build with --no-cocoa to get a Carbon-only build if you wish, but the new Cocoa renderer should of course still work with a 32-bit build.