I imagine it would be a type conversion course only? Why add the unnecessary complications of 'role' training? If the pilot were suddenly needed for operational duties I expect a quick refresher course on the F-15E and a return to his previous squadron would be the order of the day, since getting up to speed and fully qualified to fly the F-16 in combat would take an unacceptable length of time by contrast?
Others in a far more knowledgeable position will no doubt be along to comment shortly...
-RP