Requirements
- Mac OS X 10.3 or higher
- Python 2.4.x installed to /Library/Frameworks/
- Pyrex for Python 2.4

Pyrex Builder X for Mac OS 10.3 or higher with Python 2.4
Version 1.5.4: pbx154-mac-py24.dmg.zip
- MD5 Checksum: 45ebad94d03fd2f67b6faa34a4e7e8a4

Source
While Pyrex Builder X isn't an open source project, I will gladly provide the source files to anyone who's interested. Just send send me an email, and let me know what you plan to do with it, if anything.