Was the driver included in the ROM at all? That would be the first place to check. The Lumia 928 has FM disabled, but everything is there for it to work. For the 928, settings were located in the registry, I'll edit this post when I get the chance to find where everything was at. I also had another thread here about fm, but there wasn't any method to modify anything. I believe all I did was just ran a string search for FM in the reg files and inside the driver, I just looked for any and all strings in it.
Its late here, so I hope my memory serves me well.
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