Hi Allan,
I'm working on something that relates to your goal.
You could do it like this:
1. Run %mduextr to extract information from the Metadata Server and output to a MASTER library (new library):
%mduextr(libref=MASTER);
2. Modify the UserID column of the MASTER.LOGINS table with the info you need.
3. Run %mduextr again and output to a TARGET library (new library). This will be your current unmodified SAS Metadata library
%mduextr(libref=TARGET);
4. Run %MDUCMP to compare your MASTER (with changes) to your TARGET (unmodified) data. This will generates tables representing the changes that needs to be made to the metadata. You'll need a CHANGE library (new library).
%mducmp (MASTER=MASTER, TARGET=TARGET, CHANGE=CHANGE, EXTERNONLY=0);
5. Run %MDUCHGV to check if any changes introduce integrity problems.
%MDUCHGV (TARGET=TARGET, CHANGE,CHANGE, ERRORSDS=name);
When everything checks out, and you've done many, many tests (this is crucial metadata after all!), final step:
6. Run %MDUCHGLB to load the changes and update the metadata
%MDUCHGLB(CHANGE=CHANGE);
SAS Support has a lot of info on these macros.
Good luck!