Does anyone know how to do this?

OS: WinNT4
Browser: Netscape 6

Situation:
We want to standardize on JRE 1.4.1 but some of our clients web applications use JRE 1.3.1 and they won't run with the newer VM. So I need to launch Netscape with default plugin as 1.3.1 for some apps and default plugin as 1.4.1 for others before directing the Netscape shortcut to our clients URL.

Ideally, I would like to run a client logon script that makes a registry change to set the default JRE plugin to either 1.3.1 or 1.4.1 BEFORE Netscape launches and goes to our client URL.

Does anyone know which reg keys does this? Is there a better way?

Thanks.