If it is registered in your own country you do not ned to register it here.
Your best bet is to make sure you have current title/ownership papers and valid registration for the bike in your current country. Then it just comes in as a temp visitor import.
I would suggest that it is near impossible to register a foreign bike in Chile.
1998 E350 Quigley Diesel Ambo Camper For Sale
63 R60/2 BMW hack, 2 Dakars & K12LT