Disclaimer: This may be slightly different at other airlines.
If they're upgrading on the same aircraft that they're currently flying they go through a somewhat abbreviated sim syllabus. Instead of 7 sim periods and a checkride, they get 5 sim periods and then a checkride for a type rating.
I guess the sim periods really aren't abbreviated all that much considering all the info is still covered, only in a busier and more compact format with less periods.
In addition, the new Capt has to complete 25 hrs of IOE (Initial Operating Experience) flying the line with an IOE instructor. Transitioning Capt's can reduce this 1 hr per landing.
If your upgrading or transitioning to a different aircraft you go through the entire syllabus just like any new pilot. This includes but not limiting to:
-2 wks of groundschool CBT (Computer Based Training) to learn aircraft systems.
-8 (3-4 hr periods) of FBS (Fixed Base Sim) sitting in the sim with no motion to learn checklists, flows and non-normal procedures. Usually the CBT and FBS's are combined.
Somewhere in here you have to pass an Oral exam by the FAA or Company Checkairman.
-7 (4 hr periods) of full motion sim.
-25 hrs of IOE instruction
-Pass a FAA (new Capt) or Company checkairman (transitioning Capt) line check.
This all takes about 6 wks from start to finish. Then your on your own!