check the nhtsa website page for importation eligibility. Everything is outlined in detail.
Used to, 10+ years ago you could import it as a separate frame and body.(i.e. no requirements on parts, only vehicles.) reassemble it on a NAS frame and be good. Now it seems to be hit or miss.
You can import it as off road use only, like the kei trucks everyone brought over a while back.
You can illegally swap VIN #s.
If you can convince customs you have a legitimate rover shop and are using it for promotional purposes or research you may be able to get one for a while.
Register it in Canada or Mexico as the rules are different there.
Edit: there are other ways, but its gotten a lot harder lately due to demand customs has really cracked down. Very specicific paperwork and using the right importers with the right rep seems to be the key. Once you're in federally, state level seems to be a whole lot easier. At least in TX, hell we dont even require windshields