Good news - well, sort of. I've managed to get the demo of Wallace and Gromit's Grand Adventures running on Linux in Wine. Unfortunately the wrapper seems to be a little wonky - it doesn't seem to like to run with IE6. Running it with the Gecko plugin seems to work, at least enough to provide a "Click here to play the game" link, which launches the game itself. Running in Windows XP compat mode is recommended, so that audio will work correctly with F-Mod. The game itself runs smoothly, at least after my initial test of it.
Hopefully the wrapper in the final release versions will work better, but otherwise things look good. Looks like another buy.