I am Danish an I bought a KLR a month ago in Clifornia.
You will need to find a US address ( ask here or advrider) and just register it there. Insurance is something you drive to an insurance dealer and get on the spot.
You will need the permanent papers to leave the state probably, so buy in a state that you wish to stay a while in and give your american contact a stamped envelope so that he can mail you the registration.
easy easy if you find someone to help you.
South East Asia, USA, Central and South America and Scandinavia.