Ah yes your right. Looks like I interpreted it wrong.
If that is the case then you need to program your cars VIN into the replacement immobilizer unit first. You then need to extract the pin code from the module, and then program a new key (no old ones). If its a new module purchased from dealer you will need to set country code and pincode prior to doing the programming. This can be done with quite a few tools. You can use tools such as xprog to read the 908 mcu or you can use some tools via OBD2 such as DMAX, AVDI or TCODE to name a few.
On a side note the real dealer tools DRB3 or Witech with DRB3 emulator will not pull PIN codes directly from the car and needs a separate process of retrieving the pin through dealer network or NASTF for aftermarket before you could program any keys using them.