Someone asked me about this at RoundUp a few months ago, and I'm just now getting around to publishing it. I've just posted a tip for creating a two-celled note style table for a given paragraph style on the WebWorks wiki.
The implementation uses the wwtransform:super resolver. We are working to make this the blessed way to do overrides in ePublisher. We are working on formalizing the implementation for the 2009.1 release.
Enjoy and please report any problems.