The long answer is you need to determine what version of python you are running, then download the appropriate binary for your platform and version of python. I strongly recommend using the binaries already made on the wxPython web site, (http://www.wxpython.org/download.php#binaries) (scroll down past the Windows binaries to find the Mac stuff.)

Use the "Universal" binary for your PPC machine, like Apple says: "When you see the Universal symbol on Mac applications, that means they're made to run on both Intel- and PowerPC-based Mac computers."

Hopefully that will work for you!

Regards,

Jeremiah