Hi David,
Even if it were possible to use the Unit ID and Unit Code from the Zipabox you should reuse them. That will make the rolling key go out of sync and will give problems.
The motor needs to be programmed using a Unit ID and a Unit Code. You can simply make up your own combination. The motor can be paired with 10 or 16 (I’m not sure from the top of my head) remote controls (Unit ID and Unit Code combinations). So as long as you don’t exceed the maximum number of Unit IDs and Unit Codes stored in the motor you can simply add one for the RfxCom. Just make sure that for each motor you use a unique combination, otherwise all motors with the same combination will start moving (unless that is what you want of course).
Check out this topic: Howto: OpenHAB2, RFXCOM and Somfy RTS Rollershutters
I’m currently close to a deadline for my thesis, so I can’t promise that I have time to visit the forum the coming days, but I’m sure there are others who can help you out should you have any questions.