PCM1 Radio Code - How to obtain?

[StumptownRider]

Disconnected the battery while I was away for a few weeks to help preserve it, and discovered the Radio Code I paid a dealer to get for me a couple years back isn't where I left it.

I have the PCM1 Navigation head unit.

Can this be obtained without a Porsche-specific diagnostic tool? If so, where should I look for the serial number needed to look it up/decode the cypher?

Local dealer wants an arm and a leg, and with a newborn I don't have time to drive to another dealer.

Thanks!