If I'm correct (and this is *ONLY* a guess), the talkbox effect is a kind of throat controlled modulation of sound much favoured by Pete Framton with his guitar back in the 70s, along with Joe Walsh and Richie Sambora. I remember some guy demoing the same product using a DX7 at BMF 1990, but couldn't tell you any more other than that. Sorry. If we're talking about the same thing, then it's external hardware - you ain't gonna get it by straight DX programming alone...