mixing alcohol with benzos is overkill for beating anxiety. with the benzos you should be able to do breathing excercises or cbt and shit if the pills aren't quite cutting it (try it, when i'm in a not using phase that shit works. i don't get scripted benzos but if i'm anxious my first instinct is to run or hit the drugs and that shit helps somewhat.)
mixing alcohol with benzos is also a terrible way to get high, i know several people who have ended up getting arrested and sent to jail or psychiatric facilities because of blackout behavior on the combo.
personally i find benzo + booze blackouts to result in much more fucked up (and completely idiotic) behavior than alcohol blackouts alone.
but overall, blacking out sucks, and therefor this combo sucks.
the problem is once you have the pills in you and have a few drinks your judgment goes from, let's say a 7 on a 1-10 scale when you were sober to a 1 while on the benzos and booze. then you end up shoveling more pills in your mouth, drinking more booze, blacking out, then end up stealing something in broad daylight in front of several witnesses, passing out in a store, taking a leak in front of little kids, or some other stupid criminal act.
in harm reduction there are a lot of dangerous combos that useful advice can be given for that will make them less dangerous.
benzos and booze, to me, falls in the same category as dxm and ssri's:
just say no.
while they won't interact in a nasty way like dxm and ssri's they potentiate each other exponentially. there's really no way to be smart about it unless you have one and only one dose of the benzo, only a small amount of alcohol available, and someone baby sitting your ass (who is much bigger and stronger than you) to make sure shit doesn't get fucked up.
and on top of all this it's really not even fun.