Well, you can set a time frame for each slide before moving onto the next one, or you can create a track (with the presentation slide)to jump to–adding a script to it, then add a button to the track to jump to the next track (or presentation slide)and so on… You can create nice looking buttons in Photoshop and then import them into your DVD authoring application, this requires a little more developing within your DVD application, however!
-Oc-