First up you'll need a hex editor (the only useful tool at the moment), then I recommend you take a look at some of the mod release threads where we talk about specific modifications we've made, there are some examples which should get you started.
SWBF Mod releases, Guides and FAQs brought to you by the Gametoast team: .-=www.gametoast.com
-- No blood for oil!
-- Carpet bombing Afghanistan and occupying Iraq does nothing to ensure anyone's "freedom". (Freedom from what exactly?)
I am 75% addicted to Porn. What about you?