Connecting camera to computer to film
Are you trying for photo of video.  For video, it seems likely that this functionality is not well supported.  I took a look at the code for Pentax K-R and it is simply grabbing a buffered image from the camera for display, but this doesn't work well for video as it a) doesn't have audio and b) doesn't have reliable frame rates or updates.

If you simply want to capture still images, then using PK Tether as it currently is would work fine.

If you want video, your best bet is likely going to be to use HDMI out if it has it available and capture that output on your computer using an HDMI capture device, such as the Matrox MXO2 or Black Magic Intensity.  Alternately, if quality isn't a major concern, you could us AV out functionality and capture a lower quality feed.