The initial version of this has been committed. There were a few issues I encountered which I couldn't solve easily:
1) When the rule attribute XML is printed out, the carriage returns in the XML text are not honored so it is displayed to the screen all mashed together. I assumed by tagging this as a text area it would be rendered appropriately but that was not the case. I need to figure out how the KNS handles text area data with multiple lines currently and (if it doesn't handle it properly) look into how best to implement this to satisfy the requirements.
2) I need to figure out how to preserve the "XML Export" options from the lookups. It shouldn't be too difficult for the single record export as I can just override getActionUrls(). However, I'm not sure how best to implement the global XML export from a lookup. There appears to be a way to hook into display tag to create custom export options, however we really only want this export option to show up on KEW lookups since it's specific to them and I don't think it's possible to display the export option conditionally with display tag.