Installing 'TruStone' veneer, directly on painted drywall?
Probably not a good idea. As you said, the stones are heavy. If you could guarantee a solid rest on the floor, maybe, but I'd simply cut out the drywall a few inches inside your stone area, replace it with 1/2" cementboard, and call it good. This would be simpler than the wire lath business. I'd float backing at the joint of the cementboard and drywall to firm things up. Half-inch plywood strips would do well.