You want to do that? Really? :w00t:
Finally someone like myself!
Register an account here first and PM me, then I'll PM you all materials on altering BT1 that I managed to find over the net.
k:
Oh, yes, you'll need a hexeditor too. Hex Workshop will do just right (used it myself)
PS. I had some serious fun there. The game has a few limitations, though. First the name length of mechs (you cannot alter them beyond original ones), second - you only can have 10 weapons total. No more.