I packaged up the code changes I made to Alex Gorbatchev’s excellent dp.SyntaxHighlighter to make it work with PunBB. It is available for download (example).

The modifications basically boil down to two things:

1. Hardcode the type of code (since it isn’t settable through BBCode).
2. Work with the HTML generated from [code] blocks.

Instructions are included in the .zip file; feedback is welcome.

Please post support questions in the thread in the PunBB forums.