No help from AKL, but if the busses are still running to MGM (I think they run for at least an hour after MGM closes), you can walk or take a boat from the Boardwalk area to MGM and then take a bus directly to CSR.
Or, if you have parkhopper passes you have already used that day, you could enter Epcot at International Gateway before they close, then walk through to the front of Epcot and to a bus there. It's a bit of a hike, but you can make it a leisurely stroll.