Have you got a driver for it? Not the windows one either it sucks...
Try one of the drivers from rudloc, it allows you to set the controller up how u want. i.e. analog inputs or digital etc.
There is links to good xbox controller drivers in the above link
Hope that helps... you need to make sure you setup the controller properly in the driver setup before trying to configure it in LFS. i.e. triggers as analog not digital and on seperate axis.
I never had a drama at all with the xbox controller, once it was configured in the drivers properly. I'd sugest reading the readme files of the drivers carefully and make sure it works fine first Other than that you are not giving enough information for me to actually know what is going on, on your end