irclone took advantage of the "clone" feature on the mx-500.
You can clone one mx-500 to another (via ir), so the
irclone folks (and others) essentially reverse engineered
the ir data stream that was being passed during the cloning
process. They built a box (that connected to the PC via
USB) that could send and receive this ir data stream and
wrote software that could interpret the data. The software
was similar to the current software from URC. It was
really quite slick.

Ron