Well....like was already mentioned you need to know where you intend on competing (or hypothetically competing at least) in order to know what to look up since some rules can vary greatly circuit to circuit. Your location is listed as OK. The only circuit I found for that state is the Mid America Performing Arts Association [www.mapaa.net]. They have their Contest Information and Rules listed here:
http://www.mapaa.net/ContestInformation_PolicyStatement.doc
If you're just looking for official WGI rules, they sell their Adjuducation Manual and Rulebook on their website [www.wgi.org] for $15.00.
If you are just looking for some rules in general that may or may not pertain to you or what you're looking for, a similar topic can be found here:
http://www.drumlines.org/threads/showflat.php?Cat=&Number=46541&page=&view=&sb=5&o=&fpart=1&vc=1 and on the first page toward the bottom there is a link to the Rules Section of the MCGC.
For anyone else looking for similar things....everything listed here can in fact be found by going through wgi.org.