I couldn't edit without it anymore so it was one of the first things I did after getting VP8. I selected my custom settings, clicked on Options below the window and from the menu selected Change Target Application. It popped up a browser in which I pointed to Vegas Pro 8.0>vegas80.exe. Done
Did you go the the Shuttle Pro Control Panel and select Options > Import Settings and navigate to the C:\Program Files\Sony\Vegas Pro 8 folder and load the appropriate Shuttle Pro.pref file?