I know how to get it.
On eBay, there is someone who is constantly selling this dvd, and Parent Trap III. Whether or not it is legal... I don't know, they have a whole thing in their pages where they sell it about some particular law that states that if a movie was never released on dvd, it is not illegal to distribute it. If you really want the movie though, I guess this is how you can get it. I have read that the quality of the dvd that they sell is pretty decent, for the most part but I don't know.
Just thought I would share.