Hmmm..I'm not sure which bits to change.
I've already got the bit that includes arcade.php changed to include ibproarcade.php. (In the plugin).
I've also tried adding that code manually both to index.php in the forum, and also to arcade.php (the v3arcade file), but to no avail.
I'm not sure what other bits might need adapting.
It might be that it's not "meant to be", but I haven't given up yet.