I have caped many a deer. How much different (except for size of course) is caping an Elk?

Blue

Nothing, just more time. It may be more difficult getting the skin away from the bases of the antlers.

As stated in the above post,time is your biggest consideration here.Big animals like elk and especially moose take a long time for the average guy to cape.Because the heads are so much bigger they are more awkward to deal with so it really pays to have a second set of hands to hold things IF you can get someone to commit to the time required.When you're turning the ears on a moose your arms can almost half disappear into those huge ears but the procedure is still the same.
I helped a friend cape a bison back in '97.Just cutting up the back of the neck was a chore because of the thickness of the wool there.It took two guys to untangle it and when we straightened it out the dreadlocks were over 8" long.
As a general rule,when we bring a large head back to camp to cape by noon or so,you can usually count on whoevers doing the job to be tied up for the rest of the day.None of us are what you'd call expert capers,however two of my partners are better than average having done dozens of heads between them.
Just take your time and I'm sure that you'll have no problems.
Dave

What David said, with one addition. The larger the head, and even more so on a moose, the more nostril you should turn so it can be wrapped up into the nose on the mount. You can see a good bit of the interior of the nostrils on a moose mount. BD