Hi Chandan,
I am not sure if I understand your question - you have SEP clients that do not have Internet access, but wish for them to be brought up-to-date?
How many clients need updates, or is it a whole SEPM + SEP clients subnet?
If it is just one or a few clients, bringing an Intelligent Updater (.exe) in on a USB key will bring the client up-to-date. An even bette roption would be to enable 3rd party distribution and drop the .jdb onto those clients.
If it a large network, there is a solution with LiveUpdate Administrator 2.x.
Please do add more details, when time allows!
Mick