According to this post from avsforum, HDPLEX internal IR receiver is confirmed to work with Logitech Harmony One Remote.
You could locate the code by using Microsoft as the manufacturer and MCE-1039 as the model.
Tag Archives: Internal IR
HTPC HardwareHDPLEX Internal MCE IR reciever is confirmed to work with Logitech Harmony One Remote
February 5, 2011 – 7:55 am