http://zauberklang.ch/filmcolors/timeline-entry/1445/
"With the introduction of the chromogenic Eastmancolor negative/positive process it became possible to shoot with a normal one-strip camera. Three b/w color separations were produced from the Eastmancolor negative and printed by dye transfer on blank film"
http://arstechnica.com/business/2010/05/star-wars/
"Kaminski points out that a duplication of the original negative—commonly printed for the sake of protection—doesn't seem to exist for Star Wars. Something better was created, though: separation masters. "These are special silver-based copies that do not fade, and in theory should be almost identical in quality to the original negative itself, so even if the negative was destroyed you still have a perfect copy (which is the point of making the separation master)." Duplicates from these prints were used to replace damaged sections of the negative during the restoration before the release of the Special Edition."
So essentially the Technicolor film would be created based on the color separations, which were printed on Eastman stock.