When I recently received a hand-me-down APIC controller from a fellow friend, it came with a very old version of CIMC and it was impossible to upgrade the Controller due to the Java incompatibility and browser issues. Yes, I tried three different version of operating systems and multiple versions and security settings within java and finally gave up on using the virtual KVM to mount the APIC ISO. I had an old USB DVD player lying around at home, and the solution was very simple, and old school!
Burn a DVD with the APIC ISO image, and boot the APIC controller with the DVD in a USB attached DVD Player, a couple of prompts later, you are upgraded. You could also use the same trick to upgrade the CIMC.