Upload the JRE to the Bes server (Personally I like using the Windows Software distribution wizard for this to upload & generate some of the action that I’ll need)
Create a copy of the Java Runtime Environment 6 Update 21 fixlets you want to deploy as 6 Update 20 (JRE<6, JRE5&6, JRE 6 Installed)
Relevance for JRE<6 stays the same, just change the action for the download, extract, wait and action requires restart
Relevance for the other 2 fixlets needs to be modified from evaluating against 6.0.210 to 6.0.200. Again change the action for the download, etc.
I did the same. I made a custom copy of the update 20 before it expired and kept the .exe around so it could be copied and renamed in it’s respective folder on the BigFix server.
Our application developers have only tested up to 20 so far so that is where I locked us in for now.