Unfortunately such a feature currently does not exist at present. If you can submit a case (on-line) we can write this up as an enhancement request.
The only way to manipulate privilege sets in an automated fashion is to use the DTK, as documented in the PVCS Developer's Toolkit Reference Guide, but that is a rather complicated route that would require you to write a native application.
If all the changes you are trying to make are contained withing a single Access Control DataBase (ACDB) file, then you could temporarily take that ACDB file, dump it as text, perform a search and replace of the values you want to change (carefully, as to not break the syntax) and create a new ACDB file out of the text file.
The command you would need for this are:
<i>VM_Install_Dir</i>\vm\win32\bin\admin\readdb -a"<i>YourACDBFile</i>" > ACDB.txt
and, after you modified the ACDB.txt file:
<i>VM_Install_Dir</i>\vm\win32\bin\admin\makedb -a"<i>YourACDBFile</i>" ACDB.txt
Note that messages like:
makedb: promotion group "DEV" ignored on base privilege "VIEWARCHIVEREV"
makedb: promotion group "DEV" ignored on base privilege "VIEWACCESSDB"
are not cause for alarm. They merely indicate that a privilege set that is restricted by promotion group also contains base privileges that cannot be restricted (as they do not relate the revision specific operations).