Surely that again is not the point? You can stick any old pickups through a couple of preamps to eliminate the interference between the picksup, or even just buy some EMGs which have that already done.
But that doesn't give you individual string buffering to get rid of inter string loading. That is the wals main feature. Not knocking wal at all, I am sure there basses are nice, played one once, it was pretty good, seemed a bit like an overwater really, too much for me to be interested in (and also too heavy). Unplugged, nothing hugely different. But plugged in, elecronically, unique.
I think the idea of doing a 'wal clone' would have to be about the electronics.