software synthesiser for emacspeak

[Adams]

Hello
I'm trying to choose the software synthesiser for emacspeak.
I would like it to have the following features:
1. Sound clear
2. Easy to install and upgrade

I have the following synthesisers installed on my system:
1. festival with mbrola support
2. flite
3. eflite

Festival sounds best for me, eflite the worst, flite is quite good.
Unfortunately I couldn't find the clear documentation on how to launch
them with emacspeak.
Could You indicate some good docs of how to do that ?

Thanks in advance