Where you want the video to "pause", open it in Vegas, set the preview to "best" copy the image to the clipboard and import it into DVDA as a background. Do this for each time you want the video to pause. Once you do this, put a button that when pressed will pick up at the next chapter point.
You might be able to set an end action for chapter points or regions, I am not sure as I do not use that function, but I do know that you can take the video and cut it into those segments in Vegas and import them back in so that you can set the end action to point to one of those "freeze frame" menus you made as stated above.