Not used protools, still no VST support for it? An alternative would be running a standalone app and rendering a wav of the vocoded signal and then just loading that as a sample into protools. I don't use vocoders in my music, but when I was messing around with them a few years back, I found this was quite good and the price is right:
http://www.analogx.com/contents/down...r/Freeware.htm