<p>Has anyone got the steps to compile darwin libraries on gcc for arm on ubuntu?</p>

There is a
site
that provides patches for and arm darwin kernel.
Darwin on ARM develops and provides patches for the Apple Darwin-xnu kernel sources so that it can be cross-compiled to run on an ARM processor.
This ubuntu
forum entry
shows how to install the arm-linux-gcc cross compiler.
Put the two together and you should get what you asked for.