Someone's probably come up with this one already but...

Every system normally has some sort of systemwide logon UDC (OPTION LOGON).
Patch this to
run a command file which "logs" the user details you want to a flat file...

:HELLO MANAGER.SYS
....
....
:
:BUILD USERLOG;REC=-80,,F,ASCII;DISC=25000;CIR
:

Then create a command file which does something like...

FILE XYZZY=USERLOG.PUB.SYS;ACC=APPEND;SHR;GMULTI;LOCK
ECHO !HPJOBNAME !HPUSER !HPACCOUNT !HPDATEF !HPTIMEF >*XYZZY
RESET XYZZY

Which is executed every time the user logs on. This will give you your base
data to analyse. Alternatively
you could use a log anaylsis tool (from the CSL) to analyse the system
logfiles and extract the data
from there.

Mark Wilkinson.
Sony Pictures Entertainment.