Place a 2- or 3-quart bowl of water in the freezer and let freeze overnight.
Peel 6 lemons with a swivel-bladed vegetable peeler, trying not to get any of the white pith.
In bowl, muddle the peels with 1 1/2 cups superfine sugar and let stand for an hour for the lemon oil to leach out.
Juice the peeled lemons and add the juice to the sugar mixture, along with the tea.
Strain out the peels and pour into a 1-gallon container.
Add the rum, cognac, port and Grand Marnier, and refrigerate for at least 1 hour.
To serve, unmold the block of ice into a 2-gallon punch bowl.
Add the chilled punch stock and top off with the club soda (or, if feeling adventerous, Champagne).
Garnish with grated nutmeg and 1 thin lemon slice.