hi
thanks for prompt reply.i got some clue from your reply.
i was thinking that script will run even if i leave <ALT> mode.thats why i was concerned but after doing some experiments and above link i came to know that the scripts i load from scripts folder run only when i am in <ALT> mode.it does not interfere with any other setting like shutter speed overriding etc.for that setting i can leave <ALT> mode and they will be available.
thanks for reply