Char the wood until well-blackened. Chop up into pieces small enough to fit inside a one quart mason jar. Fill jar with wood chips, cover with Campari, seal and set aside 2 weeks.
After 14 days, strain liquid through cheesecloth three times. This will yield you plenty of cedar-steeped Campari for future cocktails, and also tastes just fine alone on the rocks.
Add cedar-steeped Campari, rye, shery, and vermouth to a mixing glass.
Add ice halfway to the top of liquids. Stir quickly, just long enough to briefly dilute the ice.
Strain into chilled champagne coupe. Finish with lemon twist.