I planned to install Roller in my centOS which need tomcat6. But centos5.3 has tomcat5 in it's yum. So I have to install tomcat6 using other way. I searched and found this good install guide in:
     http://cloudservers.mosso.com/index.php/CentOS_-_Tomcat_6 ( or http://de0ris.blogspot.com/2008/08/installing-tomcat-6x-on-centos-5.html )
which give detail instructions. I choose some important part and paste here in case for late use.

1.  install appache ant:  （note： download and put the tar file in /usr/share first ）

   tar -xzf apache-ant-1.7.1-bin.tar.gz







2. install tomcat:（note： download and put the tar file in /usr/share first ）







tar -xzf apache-tomcat-6.0.18.tar.gz

3.  create a symbolic link for Ant so other applications can easily find it. Be sure to select the correct version when you create your link.

ln -s /usr/share/apache-ant-1.7.1/bin/ant /usr/bin

4. set JAVA_HOME:

cd /usr/share/apache-tomcat-6.0.18/bin



vi catalina.sh

enter insert mode. Enter the following:

JAVA_HOME=/usr/java/jdk1.6.0_14

Test:

cd /usr/share/apache-tomcat-6.0.18/bin



./startup.sh

5.Automating atartup:   Right now Tomcat will not start up on it's own so we need to create a startup script for this. To do this:

cd /etc/init.d



vi tomcat

Press i to enter insert mode and paste in the following:

#!/bin/bash



# chkconfig: 234 20 80



# description: Tomcat Server basic start/shutdown script



# processname: tomcat



JAVA_HOME=/usr/java/jdk1.6.0_14



export JAVA_HOME



TOMCAT_HOME=/usr/share/apache-tomcat-6.0.18/bin



START_TOMCAT=/usr/share/apache-tomcat-6.0.18/bin/startup.sh



STOP_TOMCAT=/usr/share/apache-tomcat-6.0.18/bin/shutdown.sh



start() {



echo -n "Starting tomcat: "



cd $TOMCAT_HOME



${START_TOMCAT}



echo "done."



}



stop() {



echo -n "Shutting down tomcat: "



cd $TOMCAT_HOME



${STOP_TOMCAT}



echo "done."



}



case "$1" in



start)



start



;;



stop)



stop



;;



restart)



stop



sleep 10



start



;;



*)



echo "Usage: $0 {start|stop|restart}"



esac



exit 0

Be sure to change the following items in the above file:



* JAVA_HOME path



* TOMCAT_HOME path



* START_TOMCAT path



* STOP_TOMCAT path

Once you have those changes made, save the file and quit.

Now we need to change the permissions on the file.

chmod 755 tomcat

We need to set the script to start with other system services and set the runlevels.

chkconfig --add tomcat



chkconfig --level 234 tomcat on

You can verify that it is listed by typing chkconfig --list tomcat.

tomcat         	0:off	1:off	2:on	3:on	4:on	5:off	6:off

Test your shutdown and startup script.

sudo /sbin/service tomcat stop



sudo /sbin/service tomcat start

Tomcat 6 should now be installed under CentOS.