No, it means that this is used in the speaker's dialect. The verb in your example is 'to get whiskeyed up', not 'to whiskey'.
I'd imagine it's only applicable if he's drinking whiskey, but I'm not familiar with the term.
I have heard people say "when he's beered up" or "when he's vodka-ed up" meaning "When he is drunk on beer" or "When he is drunk on vodka". It's certainly colloquial and I wouldn't recommend using it.