The log4j-boot.jar is a special log4j for the bootstrap process. This cannot be changed as you will break the bootstrap process.
In the server/instance/lib directory is a log4j.jar - it should be 1.2.8 and should contain the chainsaw classes. You should be able to access the chainsaw classes from this library. If it is not the log4j-1.2.8.jar distribution, you should be able to change it for the latest version. However, the JBoss 3.2.x source distributions contain this version so I am pretty certain it is the 1.2.8 version in the binaries.