I am currently impressed with myself. Have managed to roll my own BOINC. Built 7.15.0 from source on my Ubuntu desktop. Be warned! If you know as little as I do, it takes a long time with running things, finding out what is missing from the errors and then installing them and making sure they can be found.

Against that I am sure that there are those more au fait with the dark arts of Linux who could do it with many fewer iterations. I have no idea if building the Windows or Mac clients from source is as difficult or not.