Hi BC,
As you have discovered there is no "built-in" functionality to do this in CCM. I think you could do a couple of things to workaround this issue. You could add a second non-DID line to each recipient's phone that is reserved for Transferring priority calls to. Each user could also set a Distinctive Ring on this secondary line to add an audio indication to go alone with the "Bat Line" flashing.
Or
On the Reception phone add a new line with a CLID of "Priority Call". When the Boss calls in, have the receptionist do a quick double transfer. First to the new Priority Line button and then to the recipient so the display shows "Priority Call" :)
I know these are less than perfect but would surely acheive the desired result!
Hope this helps!
Rob