If you have access to the WordPress site via FTP or means other than the WordPress front end, it shouldn't be too bad. Just copy the output files to the site and create a link from one of the site pages to the WebHelp or other start page.
I used to be involved with a church web site that worked that way. The main site editor didn't understand WordPress, so there were many pages she edited outside of WordPress and used DreamWeaver to do it. The site was a mish mash combination of odd pages.
Thanks for the quick replies.
I think we might have found something - see http://zed1.com/journalized/wordpress-plugins/dita-to-wordpress-import-tool/
I will report back on how we get on.