can yours be used to reverse engineering SNES games?
Feed it the rom and have it split out c code?
If you make sure the binary starts at address 0, and put in the right entry point (which will be somewhere in the SNES ROM), then it should decompile it fine.
Your first step will be to use the left-hand portion of the window to disassemble the NES ROM, and then once assembly files have been created, you decompile them on the right of the window. (this is all in the documentation of course).
It should be possible to make a 'CPU module' for the decompiler which takes into account the features of the 65C816 (such as 16-bit registers).