Probably I understand your problem. In our shop too, they would use MIPS to say CPU usage "This job is using too much MIPS" ...
What you actually mean is CPU time. I am not sure if you will have the means to know the CPU usage by user, your opps team may get you that. But on a day to day basis you can check the jobs in spool to get that::
n JESMSGLG of a completed job
--- WEDNESDAY, 17 JUN 2009 ----
IRR010I USERID XXXX IS ASSIGNED TO THIS JOB.
ICH70001I XXXX LAST ACCESS AT 20:53:31 ON WEDNESDAY, JUNE 17, 2009
$HASP373 MYJOB62D STARTED - WLM INIT - SRVCLASS BATCHHI - SYS STXX
IEF403I MYJOB62D - STARTED - TIME=20.53.40
- --TIMINGS (MINS.)-- ----PAG
-JOBNAME STEPNAME PROCSTEP RC EXCP CPU SRB CLOCK SERV PG PAGE
-MYJOB62D MYSTEPD1 STEP0010 00 77 .00 .00 .02 243 0 0
-MYJOB62D MYSTEPD1 STEP0020 00 2119 .01 .00 .23 46651 0 0
-MYJOB62D MYSTEPD2 STEP0030 00 80839 .03 .00 1.15 139K 0 0
IEF404I MYJOB62D - ENDED - TIME=20.56.40
-MYJOB62D ENDED. NAME-HKG TOTAL CPU TIME= .08 TOTAL ELAPSED TIME= 2.98
$HASP395 MYJOB62D ENDED
You can see the stepwise CPU usage in min (.00, .01, .03 in this case) though most quick steps will show 0.00 and at the end the total CPU usage 0.08min in this case, though the total execution time was 2.98 min.
Also If you do DA (Active users) in SPOOL while the job is in EXECUTION you monitor the CPU usage, identify if it is looping & cancel it if required. This is specially helpful if you setup allows your to code JCL TIME parameters.
Hope it helps,