Hi Fuzzy,
It's been a goal of mine for some time to get my AI off the ground... Having a new little one I didn't solder and bolt together with my own hands and who doesn't have an off switch has gotten in the way...
Here's the info on creating Festival voices:
http://www-csli.stanford.edu/semlab-...m/festvox.html
To be honest, most of it is EXTREMELY Academic as it was produced for work at the University level to better understand speech synthesis...
Nonetheless, if you persevere and spend a lot of time looking up terms, you'll probably win out.
Regarding using Vocoder, I could find little to no information surrounding actually using it in conjunction with Festival or Flite.
Best of luck!