There's default support for XBox controllers, but it's terrible.
Theres some drives you can get that i use, but it's a pain in the ass to set up and you have to restart your computer every time you unplug the controller.Also you could make circle crouch for your suggestion.
https://sites.google.com/site/carlkenner/glovepie/ - ive used this with the wiimote, should work with ps3
I don't have an XBox controller anyway. Or an XBox.
DS3 tool has a function to emulate Xbox controllers.
So I could make Nitronic Rush think I am using a XBox controller, but really I would be using a PS3 SixAxis. woot.
Glove is way overly complicated and doesn't work for me. So...DS3 I guess