There is not going to be a "one-size-fits-all" solution to this problem. A multi-faceted solution including both technical and non-technical elements would likely work best.
The easiest part of the solution to implement would of course be the text in the vicinity of the comment box. This text would establish certain core tenets that we can all vote on with Paul.
The technical aspect of the solution could monitor how often certain users are being down voted. The down-vote history of an account could then be used to "weigh it down" somewhat, so that it takes more up-votes in the future to bring their comment to a higher position on the page.