I have the same car and the same problem.
I swapped out my stereo for a JVC with bluetooth but still want to utilise the screen in there so I've been researching on how to do it (had the car for two years now so not exactly rushing....)
The DVD in your boot will likely not play an EU region Sat Nav DVD due to the region differences, unless Toyota have had OEM region free disc players in '01. You can buy the Satnav maps from here: Official site - http://www.toyota-mapupdates.eu/
or on eBay depending on your preferences and can then try to player to see if it works.
Alternatively you could replace the player altogether with one of these (if you check the connections they seem to match up so should be an easy swap) http://www.ebay.ie/itm/Toyota-Avens...n_Car_Technology&hash=item19c56a2919
Replacing the player may bypass the Jap conversion issues and show you something on your screen and it would be a cheaper and easier way of resolving the issue than getting a new screen (or one that fits that exact size) and manually installing it yourself. The Dvd replacement could be done in half an hour with no removal of centre console necessary.
You may be asking why I haven't done this myself if it's so bloody easy? Well when installing my JVC unit I had to do some creative wiring as the original wiring harness was the Jap version which naturally had some additional wires that I had no use for at the time. Of course these wires were for the Sat Nav which now has no power to the screen as a result...I just haven't had the heart to go back in to re-wire everything since, especially as everything else works perfectly for me.
If you ever give this a go and get it to work let please let me know and I'll be straight back into the centre console to get this up and running!
I don't really care about the maps aspect TBH as Google maps is the only thing you ever need, it's more about the fact that this piece of kit is just sitting there doing nothing when it could be on and looking amazing everytime I get in the car. Celica's are very good looking cars and I want mine to look its best at all times
Anyway, update this thread and let us know how you get on if you ever decide to take the plunge.
EDIT* You can also get the discs here: http://www.satnavi.com/toyota.php
EDIT again** Here are the instructions for installing a Celica Sat Nav; not for the faint-hearted! http://www.toyota-tech.eu/aimupload...4727F6%7D/TNS%20500%20RHD%20N1RT23-F.pdf