DVD@ccess isn't the greatest feature in the world. If you do a search on this and the Apple discussion group you'll see it has fostered less than satisfactory results. You need to manually install it on PCs.
Bottom line is it won't work on all systems. Accessing files outside the TS folder is not part of the DVD spec.
For me personally, I won't do jobs like this anymore because of clients who just don't understand the pitfalls. They expect it to work on every player everytime...which will not happen.