Well first of all a carbon steel barrel would not last very long.
Wrong.
There are carbon steel 1911 barrels made from 4150 or some such alloy that will rust if left to thier own devices. But they will last as long or longer shooting them as any other barrel made from stainless steel.
The best national match barrels have always been made from carbon steel with cut rifling.
Then there are stainless steel barrels as used on many newer 1911's made from 416R stainless or similiar alloy.
I see no real good reason to put a carbon steel barrel in a stainless gun.
But if you do have a good reason, there is no reason you can't do it.
1. The barrel hood has to be fitted to the slide.
2. The locking lugs have to be fitted to the slide.
3. The barrel lugs have to be fitted to the slide stop pin.
4. A new barrel link has to be fitted to the new barrel for proper link-down without interfering with the locking lug fitting when the slide is in battery, or locked open.
In short, it is not a DIY project for the guy with a kitchen table, a nail file, and no idea how to do it.
rc