Orange Blossom mead, is fermented from orange bloosom honey, it's closer to wine then beer though it is not either.
Not having mead, 2 Tbs. orange blossom honey mixed in a dry white wine might come close. Not sure that cointreau would give the same results, I'm sure it would be good regardless.
Orange blossom mead: 3 kg orange blossom honey, small handful raisins, 5g wine yeast, water to make 4 liters. Dissolve honey in water, crush raisins then out both in a 4 liter glass jar, rehydrate yeast and add to mixture. Cover with cheese cloth for the first 3-5 days, then fit with an airlock. Everything which comes in contact with the honey must, has got to be sanitized!
There are a couple post here on mead making, for more info including saitization practices, take a look at http://gotmead.com
~ search "Sanitization" it's the key to success.