Pure spirits (vodka, rum, gin) have no carbs, but of course, as was said, alcohol burns before fat in your system. Drinking shouldn't knock you out of ketosis though, just put you at a standstill until it's out of your system.

Possible drinks:

Rum and Diet Coke (or better yet Diet Rite)
Gin and diet tonic
Vodka and Crystal Light

Depending on your tastes, I'd probably just show up with a bottle of diet something and mix it with whatever's available.

You should find that you won't even need a "few" drinks. I had two martinis soon after I went off induction and that was plenty.