You can create a dummy schedule with the following:
__ X __ MONTHLY JAN: X FEB: X MAR: X APR: X MAY: X JUN: X
JUL: X AUG: X SEP: X OCT: X NOV: X DEC: X
WEEK: DAY-OF-WEEK:
RDAY: /-0
This will give the job a schedule member with all days 'turned off'. You can 'turn them on' with the SCHDMOD screen.