Not sure if the same setup, mine is an older mechanically injected C. I haven't had to remove mine but I have studied the manual. On mine the compressor is gear driven off the cam gear and the hydraulic pump is piggybacked onto it. It is water cooled with coolant lines from the engine and uses engine oil for lubrication. It is indeed timed with markings on the gears for balance. If I remember right, it depends on the brand compressor installed as to what marks you should see on the gear. Manuals should be available online at cummins quickserve.
The lower right gear in this photo shows the compressor gear. I had an oil leak between the gear housing and engine block so lots of stuff had to be removed. The gear housing came off over the compressor gear without removal of the compressor so I would assume the compressor could be removed without pulling the gear off the shaft. I think you would still have to remove the gear cover as in this picture for timing though.
1994 Holiday Rambler Navigator