A Sun Java virtual machine is needed. You can see in Bibledit whether a correct version of Java is already present. In Bibledit, go to menu Preferences - Formatter. If the first line, about Java, says "Done", then Java is fine. You can proceed with XEP. If it says "To do", you will need to install Java as described below.
Download a Sun Java virtual machine from http://www.java.com/en/download/linux_manual.jsp.
Choose the "Linux (self extracting file)", which gives a file called jre-1_5_0_06-linux-i586.bin or a higher version
Put it in the home directory.
In the terminal, to verify the package is there, type
ls
To install the package, type
sh jre-1_5_0_06-linux-i586.bin
Agree to the license and complete installing Java.
Make a note of the directory where Java got installed. In this case this is ~/jre1.5.0_06
Note. If you install it in the directory given above, then Bibledit will find Java automatically. If you install it elsewhere, you need to enter the path to Java by hand.
Note: If you click the "Java" button to choose the Java binary, and a wrong binary is selected, it won't find Java anymore, as it was given the incorrect binary. To resolve that close the dialog, and open it again.
Note. Some Linux distributions come with their own version of Java installed. It may be quite a hassle to find out where this version of Java has been installed, and so it may be difficult to locate it in Bibledit. In case you encounter trouble to find that directory, it will be easier to just download the Java version as described above, and install it following the instructions. And moreover, the GNU version of Java, gij, is not enough for XEP. Hence, if this version comes with your Linux distribution, you still need to install the one from Sun.