Wowza Streaming Engine won't change the keyframes for "vod" files. It will simply stream them with whatever is defined in the file. You could look at creating a "pseudo-live" stream using
ServerListenerStreamPublisher, which "publishes" VOD playlists as a live stream, and which then allows you to transcode the stream on the fly, including setting a different keyframe. This may not be practical for large numbers of files though. In this case then from a programmatic perspective you could look at
ModuleStreamControl to dynamically create a live stream.
I don't have examples of how to load the schedule outside of Flash client but the source is available for customization. You can stream the output as MPEG-DASH. I'm not sure what you mean by "seekable". As it's a live stream then you can't skip through the stream. You can apply DVR-type controls by enabling the nDVR AddOn for that Wowza application, but currently this is not available for MPEG-DASH. We do hope to provide nDVR for DASH in the future though.