Idk how but i see others do it

I recommend watching the video tutorial pentaleks gave for setting up the game here:

Note that the link to see where in the willow game files you need to look is here: http://borderlands.wikia.com/wiki/Borderlands_PC_Tweaks , since gearbox deactivated the forum page on it.

Ok thanks

Penta also has this solution in the PC tweaks in guides section