When converting a PS2 controller, you'll have to settle for the default mapping for the keys since there's no way to change them. But it is the most logical configuration. The buttons are all mapped to the buttons that are in the same place on the controllers. When you convert the keyboard and mouse though, you can map any key on the keyboard to any of the button functions on the controller. This makes it really easy to play the games however you want to play them.
The Sniper Plus is quite easy to set up. You simply plug an Xbox 360 wired controller into the Sniper Plus USB port, plug the PS2 controller into the slot on the Sniper Plus, and then plug the Sniper Plus into your 360. If you're using a keyboard and mouse, simply plug those into the ports that they fit in on the Sniper Plus, plug the Xbox 360 wired controller into the Sniper Plus, and then plus the Sniper Plus into the 360. There is a list of instructions on how to program the keys that you want in the box. It is quite simple to program.