Don't even think about it.
If your computer isn't connected to any networks, how is it going to report any location at all? Even if it did know it?
IP address based Geolocation is not helpfull:
Using IP based Geolocation - and why it's pretty much useless.[
^]
So...you have to add a GPS (for accuracy) or cell-based phone system to your computer - which is going to be rather obvious, and make your computer a better target for thieves.
And as PIEBALDconsult has said: the first thing a thief is going to do is wipe the drive - preventing your software running at all...
Instead, spend the time more wisely by looking after your kit, and the money you saved (because your time is worth money, right?) in insuring it instead. And backup your data so you don't lose that if a thief does get it.