Hi,
Use the function module 'RSAU_WRITE_SM01_LOG' to lock/unlock t-codes.
To lock:
CALL FUNCTION 'RSAU_WRITE_SM01_LOG'
EXPORTING
TCODE = TCODE
LOCK = 'X'
To Unlock:
CALL FUNCTION 'RSAU_WRITE_SM01_LOG'
EXPORTING
TCODE = TCODE
UNLOCK = 'X'
Regards
Gangadhar