So I survived using the Multilingual Toolkit with the phone, Windows 8 should be a piece of cake. Unfortunately, the experience could be described as crumby.
The documentation is either piecemeal, refers to older methods or different languages or has been deleted. If the Toolkit is the preferred way, the older documentation needs to be updated and simply explained. If links must be deleted because they are out of date, there should be links to the new material. It is quite common that non MS bloggers refer to MS articles, so not providing a new link is leaving these authors hanging.
So what is different?
On the phone, adding a new language creates a new resx and a an xlf file that VS keeps in line. You only need to change the source language resx and do the translations of the content of the xlf files. When you add new strings, click on the xlfs to start translator. Translate All will only translate the new strings so your previous work is safe.
On Windows 8, there is only one resource file with an extension of resw. The rest is the same as for the phone.
On the phone the strings use binding, so once build you will see the string while editing.
On Win 8, you use x:Uid and must include the attribute in the resw file. So you end up with XAML of <TextBlock x:Uid=”AppName” Text=”myApp” and the Name in the resw file would be myApp.Text. Without the binding, you only see the content of Text and you have to run the app to see the results.
On the phone the res file is just strings. In Win 8, you can have more than just strings, you can have things like Width.
With misleading documentation, a simple example would have been very useful.
Now I get to spend the rest of the weekend trying to restructure the res file and working out if there are anymore exceptions.
John Marshall… Visio MVP Visio.MVPs.org
john Visio MVP 
WOW! I think I might just stick with wp dev! Sounds like a few too many gotchas for win8 dev at the moment? Thanks for showing us the light through all of these pitfalls! You da man!