My understanding is that to do anything related to custom OSes or custom ROMs will require source code or custom drivers for the hardware that is used in the phone. There may be projects out there that are attempting to this for the MTK SoC that is used in the fairphone, but as the hardware in each model will likely be slightly different, there will be no guarantee that all the functions of the phone will actually work. There is a whole discussion about source code availability in this thread: http://forum.xda-developers.com/show....php?t=2636257
, as well as a number of mentions of (limited) progress in building a working kernel in order threads. In short: the chances of an alternative OS for the fairphone appearing within a useful time frame appear to be quite slim.