Here's an ebuild for blackdown JDK 1.4.2-rc1. This is the first java for amd64. I have tested it with amd64 but it should also work for x86. It's based on blackdown 1.4.1 ebuild but I copied quite a bit of script from the sun 1.4.2 ebuild to get it working.
Created attachment 22526 [details] ebuild for blackdown jdk 1.4.2-rc1
err, already in portage ... I did it a different way though ;)