If you compare the bottom of an S-VHS tape and of a D-VHS one, you will see that the D-VHS one has an additional hole.
The bottom of the S-VHS casing shows a groove with one little hole in the left, and a big hole in the center.
A D-VHS tape has another little hole on the right.
So, all you have to do is drill a similar hole in your S-VHS tape. Be careful not to go through the casing, you don't want to have plastic dust inside your tape first, and then on your 30000 heads.
Of course, there MUST be a way to use the 30000 menus to do that, but I don't know it: I have only the Japanese version, and the manual is a tad hard to read:D