I can sympathise with your understandable confusion.
One of the troubles with the internet is that it is so easy to present a million pages of information to the world, but seems so hard to keep any of them up to date,
The situation as of today is this...
ALL TomToms that connect to "MyTomTom" (the so-called "NAV3" models) should now be able to load and use extra "real" recorded voices such as the ones from those three sites I gave links to.
I have done this and know it works.
But the computer-generated ones that can read out street names, cannot be shared between different models.
The only other issue (nothing to do with the new models, is that if you BOUGHT a voice from TomTom (maybe your Homer Simpson one?) then Tomtom locked them to one particular unit to stop people sharing them (just like they do with the maps).
If you know where your Homer Simpson came from, we can hopefully tell you whether it will be possible to re-use that one, or whether we can find a replacement for you.