I've recently come across this phrase in "The old gods waken" by Manly Wade Wellman, another keen observer of southern rural slang and dialect:
It doesn't mean only the ghosts of dead folk a-using around to get
into mischief ...
They've been a-using round Wolter Mounting long enough.
(1979 Doubleday edition, pp. 135 + 58)
As there is no alcohol or drug abuse in this context, I understand the phrase to be some synonym for "loitering around".
Edit: Here's another example I'vefound on this site http://www.wvculture.org/history/journal_wvh/wvh30-2.html about Appalachian dialect:
"I've been a-studying about how to say this, till I've nigh wearried
myself to death. I reckon hit don't never do nobody no good to beat
about the bush, so I'll just tell ye. Your man's hippoed. There's
nothing ails him, but he spends more time using around the doctor's
office than he does a-working."
sadly, it's without reference or further explanation of this specific phrase