As pointed out in older threads, the *free* EFM Auto-Wah is *awesome*, but apparently a bit difficult to find nowadays. I have a copy of it, so PM me if you're interested. I have also used the Sonitus WAH, but it has too "dirty" of a sound for what I was after. EFM is nice and clean and doesn't try to sound "vintage" or whatever ...that, and the Sonitus wah is not free.
Here's a link to a forum thread which includes a link to his newer version, which I have not tried yet: Here's a direct link to the vst itself (from that thread): Iza hope dees helps! :D