How are you going to provide value to the VC firm? This is key - if you're going to reach out to a VC you need to be able to convince them why it would be worth hiring you in the first place.
And the answer to your question (IMO) - it's unlikely that you'll find many job postings at VCs. They will almost all have strong networks to tap for their hires, rather than spending time on public job postings. I don't think you need to attend B-school or have a successful exit (though these things certainly build credibility for you). I do think you need to find a way to enter their network (like any resourceful entrepreneur would do to pitch them). Figure out how you can add value, then reach out and try to get a meeting. If they don't have a position now, they may in 6 months. Get on their radar.