Place cemetery tiles as usual.
Don’t add ghosts to the cemetery when playing the expansion.
These tiles have a different function in the expansion as in the cooperative game. You may place a meeple or guard meeple onto the cemetery as a cemetery keeper.
In the expansion, you score a cemetery as soon as it is fully surrounded by tiles (like a castle or cloister). Take an additional guard meeple from the general supply and add it to your own supply. You now have another meeple at your disposal.
If there aren’t any guard meeples in your color left in the general supply, then you already have a sizeable advantage and don’t get any more.
By placing this tile, you have completely surrounded the cemetery. You score it at the end of your turn, taking a guard meeple from the general supply and adding it to your own. You will have another meeple at your disposal next turn. Finally, return the cemetery keeper to your supply as well.