I have a 97 Pajero and it does have remote locking. They changed shape during this year so I am not sure if you have the new or old model. Is it the new shape?
Mitsi has the remote for other models such as RVR and GTO pre 97 so I think that you should be able to get it altyhough it may be it was an option. Check the website listed below against your VIN number under the bonnet and see waht it lists as supplied by manufacture. Then your best bet is to call a dealership or possibly wreakers and ask them about. Must be a way to install it but I admitt that I don't know much about it. Hope that this helps.
Jim
NZ
http://english.auto.vl.ru/catalog/