Updating OS to 10.7.3 with slow internet
Download the 10.7.3 combo update from here:

http://support.apple.com/kb/DL1484

Burn it to DVD (or split it and burn to 3 CDs).

Run it on the target machine.  It must already be running 10.7.0 or later for this update to install.

If you want to update other Apple software offline, this page has links to many of the common Apple updates:

http://support.apple.com/downloads