I do what you're describing, as a community it's a real mix of backgrounds. Personally I think you're best off looking for someone with an editorial background and a willingness or interest in the technical side than the other way around, a knack for spotting a story is a harder skill to learn. The other thing is that presenting those stories in anything other than words is another skillset entirely, both in terms of design and development. Finding someone that can do all 3 very well is a tall order. More recent grads coming out of journo school increasingly have some programming or stats proficiency, that would be the best place to start looking. The other place would be the more hard (as in both high quality and more technically/theory focussed) graphic/information design courses.