This is a crazy road built to unify Chile under orders from Pinochet. The most recent section to Villa O'Higgins was finished in 1998. The way we did it (from Ensenada via Ralun) was about 1300km long.
Below are files that you can open in Google Earth. The kmz file can be expanded to see the separate sections in Google Earth and you can import it into the free Garmin BaseCamp software to send it to your gps:
The last 21km section across the border into Argentina involves a boat, pushing up a farmers track for 5km, 11km of OKish riding, and 6km of pushing, lifting and carrying your bikes and bags through a forest, over streams, roots, rocks and for the last 2km, down a heavily eroded gash in the earth 'just' wide enough for your bike.