OK, there's now a zip file 'GYMV1.2UPGRADE.zip' in the same folder as the exe.
Basically as I said before I opened the source project (downloaded from the GYM website) in Visual Studio 2010, let it convert the project (the UpgradeLog.XML in the zip will give you an idea of what happened there), then added rolandinchania's changes to main.cs, recompiled it & put the GYM.exe out there.
As for what versions it will work on, I'm afraid I only have an NW-HD5, so can only say it will definitely work on that. Suspect however it will work for a lot of models if GYM works in general & it's just the folder selection that is causing a problem. Backup your current GYM.exe & try it.