I've had a quick go at this and got it working but not through the instructions above, overwriting the Contents folder seems to remove a bunch of stuff the game needs to run. Tried just replacing the Contents/Resources folder but that didn't work either.
Instead, I copied all the files out of contents/resources/data, and pasted them in the requisite folder in the app container. This will have overwritten any replacement files but left anything else. Then I just replaced the default preferences file in the Resources folder and the info plist in the root folder.
Then the game booted, but the opening menu screen with the car didn't display (but sound played as normal). I could load a save sight unseen, however, and from there on in the game seemed to be behaving normally (though I wouldn't rule out any other quirks) and I could see other players running around, hitting me with sticks while I connected my controller or congregating at the lookout :) Fun mod!