Francis,
You could use the PUC and B&O have offically stated that in future all IR codes added to the PUC will be added to the Beo5. However to date that has not been achieved.
With regards to the Mac Mini, as far as I am aware this has not been offically added to the PUC, so I would expect that it has been created and added by your dealer.
The Service Tool used by your dealer to update the PUC has DEC files which contain the IR codes for each non B&O product, unfortunately these files are in a totally different format to the XML files used with the Beo5. Nevertheless these DEC files hold ALL the necessary IR information required to create an BEO5 XML file provided you know how to translate it.
So, you could get your dealer to update your PUC and then it would work with the Beo4 or Beo5 or you could find out if they have converted it into a Beo5 XML file. I would however say that the cleanest solution would be to use the PUC.