My feedback:
1) You could narrow down needs. Imagine how hiring a "tech person" to build a cloud service is too broad.
2) Read about marketing people with technical skills to understand what they do. Decent but dated example:
http://okdork.com/2010/10/14/how-mint-beat-wesabe/
Many other examples blur lines too (patio11, SEOMoz, etc)
3) Couldn't tell if they had investors but that might be a source too. As hackers can find hackers, I bet investors can find marketers.
4) Find a successful competitor who filled the position. Write a job description based on that person's bio.
5) Consider trying out a contractor or consultant first. If having that person in the office would destroy culture, maybe you don't need them.
