There are several ways to make it run but the following seems to work best for me (I'm always open to suggestions on what to instruct people on).

For Windows:
Create a shortcut either on your desktop or your start menu. Just right-click where you want it and select "New"/"Shortcut". Where it asks for the command enter the following:

"C:\Program Files\JavaSoft\jre\1.2\bin\java" -cp "C:\Program Files\JCVS-5.1.1\application\jcvsii.jar" com.ice.jcvsii.JCVS

This assumes that you have installed the JRE in C:\Program Files\JavaSoft\jre\1.2\ and JCVS in C:\Program Files\JCVS-5.1.1\, if you have a different installation locations be sure to enter those.

For UNIX:
It is perferable to login or su as root to do all installs. In your user bin directory, usually /usr/bin create a text file called "jcvs" that has the following in it:

/usr/share/jre1.2.2/bin/java -cp /usr/share/JCVS-5.1.1/application/jcvsii.jar com.ice.jcvsii.JCVS

If you installed in different paths used those. Or if you put java executable in the user bin and jcvsii in the CLASSPATH then you're file will just need to be:

java -cp jcvsii.jar com.ice.jcvsii.JCVS

Once you have the file make sure that they are excuteable, i.e. type "chmod +x jcvs". Depending on your window manager you can easily put an icon on your desktop or menus pointing to jcvs.