Sure! Assuming you already have the game installed on the non-connected computer (if you used SDC archives, be sure to delete the file sig.bin from the GalCiv2 directory first), follow these steps:
1) Start the game; you will get a prompt for your serial and email. Provide them and continue.
2) It will fail to activate (of course) and ask if you'd like to activate by email. Click Yes.
3) Copy the subject line and big block of letters into a text file, or
into your email program, and save it off to portable media (CDR, USB
drive, floppy, etc).
4) Take it to a web-connected PC and send an email to
[email protected] with that subject line and content.
5) You should receive a reply with a file and some instructions; take
the file back to the non-connected PC and you should be set to go.