Guitar Hero 3 Wii Custom?

I have the Guitar Hero 3 Custom for the Wii. The problem is that it is the Wii. Hard as **** to mod instead of a Ps2. Anyways I got the GH3 Song Importer GUI and I have no idea how to use it!?! Tutorial pleases? (I have midis but this only supports charts. Hod do I turn the midis to charts?)