Simulating wah-wah with envelopes (or something else)?

Hey everyone. Is it possible to simulate wah-wah with envelopes or something? I don't have a wah pedal (no cash to buy one at the moment), so a VST plugin or envelope that let me control the "intensity" of it would be very useful (no "auto wah"). Thanks in advance. Regards, Fergo

I found one in my "old" vst folder that looks and sounds pretty good that you may find interesting. I think you can download it here. I haven't really used it but just now screwed around by turning on the wah pedal and holding down the left mouse button to rock it on and off, then used an envelope to do the same thing. Like Lokasenna says it will be hard to get the sound but if you don't have the budget for the real thing at least this one sounds pretty good.

Thanks a lot to everybody who answered, I really appreciate it. I tested all methods and I think "Green PreXPression" suggested by bigwoody gave me the best result. I was impressed to see that Reaper was able to identify each "knob" in the VST plugin so I can use an envelope only in the "wah pedal". Here's a test: Again, thanks! Regards, Fergo