I don't think benzos would have any positive effect on alcohol neurotoxicity, unless, as mentioned above, they induced you to drink less.
Olney's group has demonstrated that GABA(A) receptor potentiation mediates a component of alcohol-induced neurotoxicity in the fetal brain, and that benzos, which potentiate the receptor in a similar way, can have similar effects when given pre- or (I think) perinatally. However, this has only been shown to apply to the developing brain, and I think any such effect in the fully wired, adult brain, if it occurs at all, would be much less.