I found the following snippet in the thread linked farther down. Maybe it will help?
If you want to create a web-based help FROM DocBook, then you have some choices:
1. Use the DocBook xsls to create HTML Help output (i.e. the .hhp and .hhc files and the html files), then open the hhp in RoboHELP and generate WebHelp from that. I used this trick for years, but it was annoying to have one manual step in an otherwise automatic build process.
Hope this helps a tad... Rick