A few drinks shouldn't be a problem. I wouldn't suggest drinking everynight or heavy amounts while on it.
The thing is that accutane is NOT that hard on the liver. Wish i could remember where I came across this material at, but i will keep looking. Yes it can put more stress on the liver, but not to the extent that people hype it up to be. People do react differently to drugs and i also came across the rare cases of people having liver problems while on it (though it could have been attributed to other things along with the accutane, such as drinking, etc.).
I even came across people on this board using winny and other gear, while on accutane, and had little to no elevations from their blood work (though I believe they were taking supps. for their liver).
By the way, what cycle are you going to run?