Need to implement custom thread pool executor for tomcat 6.0.18 used by jboss 5.1.0 GA

Question

I am using jboss 5.1.0 GA which internally uses tomcat. I need to clear MDC values before http thread goes into the pool/waiting stage
I was searching for a way i can create custom thread pool executor by extending some default thread pool executor class which tomcat uses, to override few methods. I am unable to fine one.

Later version of tomcat uses org.apache.tomcat.util.threads.ThreadPool but not this version of tomcat. There is not such package in jbossweb.jar

Chatgpt also not helping, it is asking to extend java.util.concurrent.ThreadPoolExecutor but we will loose out on tomcat's way of handling threads, so i was thinking to extend some class which tomcat is already using, but couldnt find one.