best way to do FreeBSD kernel/userland development on OSX ?

i recently replaced my laptop with a mac, which opens the problem on
how do i do FreeBSD development (including kernel work) on it.

the option i am trying now is running a freebsd VM in virtualbox,
but it is slightly slow and probably energy hungry.

I'd like to keep the svn checkut outside the disk image but
unfortunately the default filesystem on osx is case-insensitive
so i can't do that -- unless someone shows me how to change
the filesystem conventions.

suggestions anyone ?

cheers
luigi