Hi Diego,
Yes it is a bit complicated, maybe moreso tiresome, but will be a lot of fun if you enjoy doing that sort of thing and have the time. I'm a bit busy with other stuff at the present, but as soon as I have time i will make up a tut and post it for you. The most tiresome part is that those wav files are not the same as those used in the standard garmin non-tts voices and so will have to be converted to 16-bit PCM or 4-bit ADPCM (compressed audio). Stand by (but don't hold your breath!), i'll get back to you asap.