The rar file should be extracted C:\BFXTemp
Then run the install.bat from that location.
That should be it. Did the mod run at all for you? It'll work fine in single player, but multiplayer will crash to the desktop. To toggle back and forth between the mod and your regular game... you have to run the disable.bat from c:\BFXTemp otherwise you're playing with a changed game... not just a mod map added to your game.
This isn't just a mod map.. this is a complete mod.. it changes your originally installed SWBF2 files.. a good portion of them too. To re-enable the mod, you have to run the enable.bat. This mod is really awsm.. it corrects SO many problems (even the shot register works better). Pity it doesn't work for multiplayer.