These two images might help you see where you can place the control points:
http://home.online.no/~t-o-k/POV-Ray_Images/Bezier_Patches_Stitched.jpg
http://home.online.no/~t-o-k/POV-Ray_Images/Bezier_Patches_Stitched_.jpg
You can find some more Bezier patch stitching images here:
http://home.online.no/~t-o-k/POV-Ray_Images
--
Tor Olav
http://subcube.com