The AtheOS guy de Qt ised KTHML a while back: http://www.atheos.cx/news.php3 search for KHTML. I can't find the source at the moment though. This is probably already widley out of date.
I agree with Dimi however that stubbs are gonna be the way to go however, maintaining a port isn't going to be much fun. Having said that KHTML/KJs is a lot neater/smaller code than mozilla/gecko.
Mark (goes to have his hair cut)