The most i know about doing that is that you will need a rco editor and a hex editor... Next time you get a theme with a custom visualizer see if the maker has an email, and email him to see if he'll tell you how....

Hex Editor: Here

Rco Editor:Here

Thats all i can think of at any rate. Also try asking NOFX or JohnyMckinny, they might point you in the right direction... Also be patient and nice when asking... I doubt they will reply when you offend them..