Programmers may come to jCVS with two perspectives (possibly more).
First, they may be interested in making a real client application. As much as jCVS is a nice, basic tool, it is not commercial grade, sweet software. The interface is a little klunky. The number of features is strictly a list of the existing cvs features. A real client would add all kinds of slick local interface and commands.
Second, a programmer may wish to use the 'com.ice.cvs' package library to implement code based on the cvs client/server protocol. One example might include a small Java program to manage multiple source trees over multiple remote servers.
Details on programming with the com.ice.cvs package are currently only provided via the package documents.
The Makefiles provided with the jCVS project, in both com.ice.cvs and com.ice.jcvs, are 'MKS Toolkit for PC' makefiles. These are compatible with more recent make programs, however, some older makes may have trouble.