What do you mean? It's done exactly the same in Vegas 8 as in previous versions. Funnily enough I was doing that exact effect in Vegas 8 only yesterday exactly as described in
YouTube - Tutorial Sony Vegas Sin City ( Tivo Transpo) effect
A thought occurs - you maybe have Vegas MOVIE STUDIO rather than Vegas Pro (previously just Vegas) version 8.
In which case no dice. Movie Studio has NEVER had Secondary Colour Corrector.