What is it about this JDM vehicle that you can not register it in the States? I have seen many JDM vehicles imported into California with is strict emissions, so why not the Pajero? Is it because they are are afraid the Spanish speaking people will be offended by a "Pajero"?
You CAN import basically any vehicle into the US, but it has to meet the safety standards first, which means it may have to be modified by a "Registered Importer", and then bonded for 1.5x the value of the vehicle:
A vehicle without a certification label cannot be imported as a conforming vehicle. In this case, the importer must contract with a Registered Importer (RI) to modify the vehicle and post a DOT Conformance Bond in an amount equivalent to one and a half times the vehicle’s dutiable value. This bond is in addition to the normal Customs entry bond. Copies of the DOT Conformance Bond and the contract with an RI must be attached to the HS-7 form
The process can be expedited if other vehicles of that make, model, & year have already been imported from what I understand, but I did not see any Monteros on the list... You can see more info here:http://www.nhtsa.dot.gov/cars/rules/import/