I still get the libgcj.so error even on 5.9 standard when trying to install pdftk. Locate says I don't have libgcj.so (any version), so I assume I have to download another version of java runtime or jre
For compiling java, I think you would need jdk, not jre.
(see this howto, if you want to give it a try: http://forum.vectorlinux.com/index.php?topic=7361.0
I might be wrong, but I don't think that would help either (in 5.9).
The gcc-java package is a different one and adds java compiling to gcc.
I don't think it is included in the gcc package, and it is not in the 5.9 repos.
Check gslapt to see if you have that package for 5.8.
If you do, in fact, have libgcj.so.5 inside /usr/lib, I'm puzzled....
(make sure it's 5, and if you have libgcj.so, make a symlink to it called libgcj.so.5)