Alright, after many hours of Googling, testing, and frustration, I finally have it: using the Wii Guitar Hero guitar with Frets on Fire.
I just got a Bluetooth adapter, so I've been piddling with it. Anyways, let's start.NOTE: All links in this post are either direct downloads, or to another webpage.
1. Sync your Wiimote to the computer. If you have already, skip this step. To do so, go to your Bluetooth manager, and click "Add New Device..." Then, get your Wiimote out, and constantly mash on the 1 and 2 buttons. This keeps it in "Discover mode", allowing the computer to see it. After it's reconized by the computer, select it and continue. When you get to the screen where's it says something like "set Pair code", stop mashing, then quickly click "Skip". (If you continue to hit it, It'll mess up the sync, and you'll have to restart. But if you wait, it's discover mode turns off, so click Skip in quickish manner.) Then apply any mode that allows it access to your keyboard or something. Syncing is done!
2. Connect your Wiimote to the computer. If you haven't synced it yet, go back to last step.
3. Download GlovePie
script (Right click>Save as).
4. Extract Glovepie, and open the script in it.
4.5 The way I opened it was to associate the script with it, by Double Clicking on it, it should say it can't find the prog, browse for it, then choose the GlovePie prog.
5. Click "Run" in the GlovePie window.
6. Open Frets On Fire, and enjoy!
Notes: The strum bar is Enter, so use the analog stick to select things, and use any button to select it, cept for Red (I think)
Sources: Honkey Kong blog GlovePie site
Pinning would be nice.
For those who can't connecting it after once, at least this happened to me, go to your previously connected devices and disable the Wiimote, then reconnect it.