You are using a very new version of the C18 compiler, and a very old version of Kevin's camera code that wasn't designed to work with newer versions of the C18 compiler.
Kevin's code that supports C18 version 3.0 or higher does not have built in support the camera. If you really need camera support, I recommend starting with
ifi_frc_sensor.zip and then start porting the camera code over. It may be a large task. If you just need the serial port support, it's built in to ifi_frc_sensor.zip, but you may still have to do some porting of the wii code, since I'm not sure how much the API changed over time.
In either case, you should be prepared to spend some time digging into the internals of how the code works. It may not be a quick change like it seems that you are expecting.
Alternately, if you could go back to using the version 2.4 of C18, and it might be easier.