Thank you very much for this step-by-step guide, my box is currently compiling.
However it's not a good idea to configure and compile as the root user.
In fact other projects even disallow doing so (linux kernel does so I think).
Only the last 2 steps need root permissions afaik.
So this should not take place in /root anyway, better would be /tmp (also for better speed) or just $HOME.
Maybe you can adapt the steps a little.
Edit: actually that doesn't work for me:
Edi2: Ok didn't realize it was built for raspberry pi, aka ARM.
My adjusted steps for x86 are here: