I looked into this about a year ago. Bob's assessment is right on target. The only other possibility is that the Kapture Group makes an electronic cable release which you could hook up to a flash wizard for timing, and do exactly what you desire. I'd guess the cost of this solution is around $1500 to $2000.

The least expensive solution is to use a standard cable release with an electronic kitchen timer and put a human between the two devices to provide an interface.