RIP, and peace to his family. I'm not Obama's biggest fan (although I don't consider him "worst President ever" or such) but do think he should be allowed a recess appointment to fill the seat for now. After the election allow the next President to pick to permanent replacement. That's the easiest way to keep this from turning into a cage match until the election. Theoretically I think he should be allowed to do the job himself but with the GOP holding the Senate you know that ain't happening.
Is it even possible to put someone on the Supreme Court temporarily?