Uru CC has the link go right into the fireplace itself, but MOUL's is moved to the outside. Even without a usable code/control panel it would have been kind of cool if they put in the ability to climb out and in the fireplace. But since Myst in MOUL doesn't even have the animation files for that, it would take some converting from CC...
We know they had originally intended the fireplace to be usable based on the part of the fireplace code you find in the Kadish Yeesha Vault, but my question is where the other 3 parts of the code would have been located...