I recall seeing a post that involved editing the keymap files in notepad++, but that was for Carmageddon 1, and I don't know if the values are the same for Carmageddon 2 (what with the game using a different engine and all). If anyone could help, it would be much appreciated. Thanks.

Here's the link to the post I was talking about: http://www.gog.com/forum/carmageddon_series/map_the_s_key_for_reverse

Take a look at this:
http://www.gog.com/forum/carmageddon_series/how_to_binding_keys_in_carmageddon_2