You could use the relatively inexpensive Broadlink RM3 Mini (black Bean) to do the control with IR... And it just so happens that I just released a native driver for the Broadlink devices AND an application to control a Remote Controlled HVAC system... (currently supports Fujitsu and Generic units)
The Apps/Drivers are HERE
I also did a quick search for the Mitsubishi IR protocol and it seems to be adequately documented and it should be fairly easy to add specific support for these units to the app...
