It is stored on the device, both in the file system and in the app manager. Neither of those are terribly useful though, so the simpler way is to open the XAP directly, and look in the WMAppManifest.XML file.
ProductID="{ede8d6f6-4b64-43b0-8be6-1c98def5ca85}"
As for the parameter you have to pass to make it think it's coming from the live tile, you'll either need to decompile the DLL or ask the author (or get the source code, which it would be awesome if more people just included up front).
By the way, ID_CAP_INTEROPSERVICES is already commented out of the manifest. You do not need interop-unlock for this app!