The following example shows how to create a new case on Oscar.
create_newcase --case /oscar/scratch/ccvtest/cesm2_C --res T62_g17 --compset C --machine oscar
./case.setup
./case.build
./xmlchange JOB_WALLCLOCK_TIME=0:20:00 --subgroup case.run
./case.submit
line 4. shows how to use xmlchange to change run options. For a full list of options you can change with xmlchange:
./xmlquery --listall
Note for CESM2 you can have a directory ~/.cime with your own cime files. Be aware of this if you are switching between your own install and the module install.