Is SEP all these ATM machines will have in terms of protection?? Not CSP?  IMO SEP is not the right choice of protection for machines that dont have a network connection, SEP requires signatures to be fully protected, CSP does not require signatures and would be far more robust.

If theyre not connected via a network there's only 1 other way and itll take a long time depending on how many there are.

Please mark posts as solutions if they solve your problem!

As Alex has stated above ("Thumbs Up") if these have no network connectivity at all, then new definitions will have to be placed on the endpoints manually.  The below articles tell you how to do this:

http://www.symantec.com/docs/HOWTO80903

http://www.symantec.com/docs/TECH104363
The above article will need to be used with this article (http://www.symantec.com/docs/TECH105498) to get the unmanaged client to allow 3rd party content distribution.

If the ATMs are (as is more likely) part of an isolated network with no external access, then you could use the LUA in the setup described in the below article to update them:

http://www.symantec.com/docs/TECH106254

thumbs up to above suggestion.

you should be looking for critical system protection. However there is way to update the client using internal Liveupdate server .

http://www.symantec.com/business/support/index?page=content&id=TECH123388