Actually, GUEST, you don't have to have any legal or judicial background to be appointed to the Supreme Court. Earl Warren, I believe, had been Governor of California but had never served as a judge.
I believe Bush could appoint Arnold Schwartzenegger to the SCOTUS if he wanted and the Senate consented.
Rapaire, I know the usual procedure if for Senate confirmation, even for some lower court justices, but Bush has appointed some circuit court justices during Congressional recesses, without a Senate vote to confirm. If Rehnquist were to resign during a Senate recess, I think Bush might be able to appoint a SCOTUS justice on an "interim" basis, with that justice serving till the President "got around to" sending a "real nominee" to the Senate. I really hope that's not true, but there are noises being made to the effect that it is.