I think this came up before. I have played around with a few ideas and I think I have a solid solution for you to try.
Just run a short 5 minute burn of this before you create a 2 hour masterpiece. It should work for you though.
What I did in my own test (without burning and actual DVD) is create a PICT overlay using a greyscale text and graphic.
On the actual clip of the footage you are showing on the DVD, I added an overlay picture, which is that grey scale map. Basically a white background and black graphic, solid black. I then add a button, but do not need to actually program it at all. Just leave a blank button created on the footage. Set the normal button highlight to 100% and that should light up the PICT overlay.
Make sense?
It is just like making a PICT based menu, except I am tricking it. It has no button to press, though there is a button and there is no highlight state. Just the use of a normal state, which is on 100%.
If you a need a phone call walk through, send me an email message and we can arrange a time when you can call me and I can walk you through this.