I am making a change to the core which will allow you to adjust the CrawlActions, CrawlRules and EngineActions before Crawling, per Crawl instance, just like you can with ApplicationSettings and WebSettings. http://arachnode.net/blogs/arachnode_net/archive/2010/05/06/controlling-configuration-from-code...
I added an Anonymizer plugin to the branch so you can see how this would be implemented. Don't forget to check out the DB too... (Branch is a branch, but quite viable...) This code is checked into the trunk now. Mike