The VK-C77 was a very popular camera in its day due to it's 12x zoom and fuzzy logic autofocus. Not many cameras had that feature at the time it was introduced.
If you are still looking for a solution to capture s-video and control the camera, take a look at the old Axis 2400 video server. It took both composite and s-video inputs and had a serial port to allow you to pass control command to cameras. Just connect the unit to your camera and plug it into your network with CAT-5 cable. If you want a wireless solution, plug it into a cheap access point. You can find a Linksys access point on eBay for a few dollars.
As for the AXIS-2400, search eBay. I've picked them up for $40-$50 in the past. You can download documentation from Axis at this link http://www.axis.com/techsup/cam_servers/cam_2400/index.htm
You can also still find VK-C77 cameras on eBay, or this site often has refurbished units http://industrialcamerasales.com/cart/hitachi-vkc77-color-camera-reconditioned-p-33.html