Short answer: you can't right now.
I actually happened to bring this up privately in mid-November, and after the idea floated around the Stack Exchange team, it was ultimately concluded that introducing ads of this nature isn't going to be super advantageous right now.
We're currently working on tightening down our scope and building up more of a community, so in many ways, Ask Patents is being run like a public beta. For the same reason, we just don't have enough of a following (yet!) to make running community ads super beneficial to anyone, including the advertising site, in this case SR.
I'd love to see ads introduced, and once we start developing that following I will personally ask the Community Managers to reevaluate the case, but for now, no such luck.
And just by the way,
I see from this question that there are community ads already running in the side bar.
That isn't actually a community ad, per se. It is, as I understand it, essentially hard-coded into the Ask Patents page, almost as part of the design.