John,
Depending on how your Carbine may or may not be set up for sling carry... there are, perhaps, three possible sling variations you might be able to use.
The most common for Civil War Carbines is a leather sling warn over the shoulder with a large clip/hook that is attached to the ring on the carbine side bar, commonly located on the left side of the gun.
You need to post photos, or send Two Flints copies of you photos for posting. This information might help folks better advice you.
My best,
Blair