After spending several frustrating hours trying to 'kludge' a software solution to the Mellotron(tm) in pursuit of a less terrible sounding emulation, I thought to myself, "What am I doing here, I'm not a audio software engineer, I can barely make any plug-ins work because of obscure or missing pathnames and folders, there's no reference, anywhere I could find, to the configuration I'm trying to create, there's a lot of assumed knowledge/facts and software dependences that are not documented either. And finally, what is my time worth? Is it better spent simply playing the guitar to get my best performance recorded(after the usual one or two dozen takes) or sit in front of a computer staring at menus?"
Answer to myself: Buy the Mel9, plug in, twiddle some knobs and just play.