Last time I tried this I had to use the old Managed Package Framework (MPF) APIs in vs2008 and it was so incredibly painful that I gave up and I have been scared to try again ever since. Well I tried again for vs2010 finally and managed to get it working in a single night! The new MEF based APIs are a real breeze comparatively speaking.
After an initial stumbling around period digging through tons of seemingly useless documentation I finally found an example of a language extension called Ook! And it was exactly what I needed. It also turns out that the API for doing highlighting in VS is setup exactly perfectly for the way I am providing highlighting metadata in MetaSharp. What a happy coincidence! This isn’t committed yet but it’s a very encouraging start.