In 2008 when I did my Raptor conversion I did look into the difference between the XT660 & Raptor wiring looms & ECU's it can be done very easily.
I could not find ant cheap ECU'S & looms so never carried out the conversion.
I did replace my whole wiring loom & ECU to remove my O2 sensor & used an earlier ECU with no O2 sensor, to gain full control of the fueling.
http://www.xt660.com/showthread.php?t=8478