Just thought I'd jump in to second S_13Mills' comment. I just got through setting up Flirc so my Harmony One remote can control my MythTV system (running on Fedora 21, 64 bit) together with my TV, Amplifier and Blu-ray player. I also used the Computer:MediaPC, Flirc:XBMC profile from the Harmony software. It was very easy to remap buttons from that profile and create new ones to cover all the MythTV features I wanted to use from the remote and thereafter use the full keyboard mode in the Flirc GUI to bind the remote's buttons to the corresponding MythTV keyboard commands. Once I figured out how to install the Flirc GUI software under Fedora (rpm package on the downloads page is still broken!), I got everything done in 15-20 minutes (including the time it took to look up dozens of MythTV keyboard commands).
The last time I set up my Harmony One to control a MythTV system, I practically sweated blood before I got it working; this time, thanks to Flirc, it was a breeze. Thanks!