There is a 6 PIN connector in the battery compartment. That is where the factory would upgrade the firmware and load it. But there is no consumer way to use it.

There was a hack called IRClone-MX a long time ago. It allowed you to custom program a MX500 from a PC. But that device & software has long been lost on the internet. You can still find the box once in awhile but without the software, doesn't do you any good.