Need to run Firefox with java 1.21

Good Morning,

In the institution that I work, there's a requirement to run an outdated system that runs on Java v.121. It can run either on Internet Explorer or Firefox, but there's another system that only runs with Java 1.44 on Internet Explorer. Therefore, I cannot use one browser to run all sytems.

I've tried to install one Java version in 64bits and other in 32 bits and then defined a 32 bit browser to run one system and a 64bit to run the other. But for some reason it did not work. Now I intend to try to use a portable browser with a preinstalled java in the right version for one of the systems.
Since the java v.144 system only works on IE and there's no reliable portable IE, I'll have to do the Java 1.21 on portable firefox.

I've followed the tutorials for installing JPortable and Portable Firefox, but for some reason the .ini files seems not to be read (I had to remove the 64bit folder inside App folder) and Java is not being loaded.

Is the tutorial outdated?

How to install a portable Firefox with a 1.21 portable Java version?