Phil has made attempts at contacting Logitech for specifications on the Harmony 880 remote control; however, Logitech has stated they cannot release this "confidential information". Phil had went on to apply for Logitech's developer program twice, but both times he was turned away.
Another Linux user, Paul Cutler, has even offered a bounty for the first developer that can implement configuration syncing and additional cash prizes for being able to update the device firmware and a program allows OEM IR command learning. More information on this Harmony 880 bounty for Linux is at his blog.
If you're a Linux user and own a Logitech Harmony 880, be sure to check out the links above and chime in with your thoughts in the Phoronix Forums.