I managed to build Kazehakase against xulrunner-1.9, and I'm using it successfully with Gecko 1.9
I found a patch on the following link <http://article.gmane.org/gmane.linux.debian.devel.bugs.general/442324> and I modified it according to the Kazehakase ebuild.
I attached the patch and my ebuild file to this bugreport. I hope it helps. Perhaps it would be nice to put it in the Portage. I'm sure many Kazehakase user want to use the new Gecko engine.
Created attachment 157669 [details, diff]
Patch for kazehakase-0.5.4 to build with xulrunner-1.9
Created attachment 157671 [details]
The modified ebuild corresponding to the patch
in cvs now. thanks