I've been searching for a recording of Saint-Seans' Morceau de Concert. I have a recording of the piano part that I occasionally play along with, but I find things easier to play after hearing how other horn players play them.

Have you tried to search on youtube. There are a some recordings of Morceau de Concert.

Go to this Crystal Records site.
Go down to CD377, (3rd one on the list)it is Froydis Werke playing the piece.
She has very good musical interpretations. She is a down to earth horn player.

http://www.crystalrecords.com/horn.html

Question: Are you playing this for an audition, a recital, a competetion? With Piano or Orchestra?
If you know the technique then let me suggest you play the "Sons Bouches" section using the French echo horn technique. If you don't know the technique then go ahead and play it stopped horn.