Just download the version you want and unpack it. Then use the jars (jboss-seam.jar, etc.) in its root directory in your application instead of your older seam version jars. If you need any of the jars in the /lib directory on your classpath, use them instead of others with the same name you may have on your machine.
You can also change into the root directory and type "ant" into a term/comand window. This will create a directory with the date of the day you are doing it and create the three basic seam jars, compiled with the JDK on your machine.
There are some differences to the packaging if you go from an older version of JBoss to 4.2.0.
As far as I know, this is about it.
Yes, that is what I did so now I have a directory with the date. So now I take all the jars in that dated directory and put them in the lib directory of my project and then build my project?
Thanks for helping,