Hi Rajesh,
I meant to say, create ZPROC_BUFF_MSG_02 instead of /SAPTRX/PROC_BUFF_MSG_02 which you can run in the background.
In this Zprogram, for every message which is in buffer, check if your indicator is set in the control parameter, then submit the standard program /SAPTRX/PROC_BUFF_MSG_02 which will post the event. If no indicator is set, do nothing and the event will stay in the buffer until the condition is met.
Thanks,
Vishnu