I've just finished compiling java 1.4.0 with gcc 3.2, but so far I haven't managed to get the javaplugin to work with mozilla. The browser just dies with error messages when I try to access a site with java. I think it's because I'm supposed to be preloading libraries in mozilla that are needed by the plugin. But I've tried doing that with setting LD_PRELOAD but so far haven't had any positive results.
I followed the hints on this page http://linuxfromscratch.org/~tushar/hints
which might be usefull to you if you decide to compile it anyway.
I was gonna try to compile 1.4.1 later but haven't got that far yet. I first want to try recompiling mozilla without optimizations.
If you do end up finding binaries could you post a link as I would like to test them as well.