OK, I went through all of this myself a week or so ago so I'll try and help you out.
I'm going to give you a pic of how I set it up in the XIM manager and a pic of where those buttons are.
If you don't like my setup you can always tweak it to your liking.
Here is how I set mine up as far as button binds/assignments go...

And here is how it would be if you're looking at your mouse and Nav setup (I use a G9x).

Make sure you set your movement to
Analog (Joystick) for your Nav before you start binding your buttons in the manager.