Well I did try one more thing (powering the connection block at the top of its current range) and still cannot get the IR Output to work. So the UNKNOWN IR OUT PORT (UIOP) problem will remain a mystery. I didn't try connecting the port to a meter or scope to see if it passes any sort of signal at all...I suppose that would be the next research step.

If anyone happens to open up their 990 (including Outlaw), take a look to see if it is connected to anything. In the meantime I am using the more-expensive and less asthetically-pleasing workaround of a separate IR system.