OK, so some more Symbian-related whining. I've discovered Ensymble, the pythonic package that turns your .py scripts into SIS Symbian packages and signs them. Great. And then you can send the package to Symbian Signed Online and get them signed. Great.
And here's a useful map from Nokia showing which capabilities require which forms of code-signing. You'll observe that Location - which lets you use the GPS - is available for applications signed through Symbian Open Signing Online (which lets anyone sign their own SIS for their own use).
Unfortunately, with my newly signed package, signed by both me and by OSO....I'm still being given KErr -46 Permission Denied errors. I know it's this particular call, because although running an SIS file doesn't create any traceback, it's the first one in the flow-control code and the next one fires a user notification, which isn't happening. Enough, enough, already.