Step 1: Materials
-A usb guitar controller (Xbox 360 Xplorer or PS2/PS3 Rock Band Guitar.) (If you want to use a wireless Xbox 360 guitar, you will have to get a wireless adapter from the official xbox website. ( http://www.xbox.com/en-US/hardware/x/xbox360wirelessgamingreceiver/ ))
-Frets on Fire ( http://fretsonfire.sourceforge.net/ )
-Xpadder ( http://www.softpedia.com/get/System/System-Miscellaneous/Xpadder.shtml )
-Xpadder controller images ( http://www.xpadderwave.com/index.php?option=com_remository&Itemid=59&func=select&id=6 )
Step 2: Controller Setup
Open Xpadder. Click the gamepad image at the top left corner, then new. Go down the tabs following the instructions. (You can skip the sticks and triggers tabs.) Theoretically, you only need the buttons (Frets), the D-pad, and tilt sensor, but you can also add the start button, and whammy bar (for use with fofix, which we'll go in to more detail on later.).
First add a controller image. You can get them from the link in the last step. Just click on open and find it. Next we put the directional pad. Check the enabled box and then follow the directions on the screen. Your strum bar up and down should be the same as the up and down on the d-pad. Now to add the buttons. Just press the button on the guitar, and when it appears, move it to its correct place on the image. Start with the frets and then do the whammy (if applicable), and the start button. Lastly tilt the guitar for the tilt sensor. (It will recognize it as a button) Move the button wherever it makes sense to you. the button moving is critical for the next step so don't forget it. If you press the strum bar, it should just do up and down on the d-pad. Press all the mapped buttons to make sure you have them aligned correctly. They will light up green when you press (Or tilt) them. When done it should look something like the fifth picture. Then go to the finish tab and close the window. Be sure to save the controller. (Gamepad-save as)