I haven't tested building on Mono (as noted, I just got TestKernel building), but I believe it should with few problems. I believe the only thing you'll have to do is install nasm (in addition to the normal deps) and change lines 51 and 52 of Renraku.build to:

  <exec program="mono" commandline="Obj/Compiler.exe Obj/TestKernel.dll" output="Obj/kernel.asm" />
  <exec program="nasm" commandline="-o Obj/kernel.bin Obj/kernel.asm" />

Let me know if you run into any issues.

Edit: Note, you need to have Boo 0.9.0 or better to build the code.