Extended printer settings (more than DevMode can handle)

Hello there,

I'd like to read and write *all* of the available configuration settings
a printer has. I've fiddled with DocumentProperties and
GetPrinterDataEx, EnumPrinterData and some more functions.
The registry keys are rather gibberish to me and I don't know how
to interpret them. Some of them are definitely not for being edited,
but some look like they'd store settings.

Can you tell me if this is, at all, possible?
And if so, how?

Thanks,
    Daniel Albuschat