How do I connect to a VPN network via Tor? Is it more anonymous than the other way around (VPN-->Tor)?
Actually, tor only provides a socks proxy. So your OpenVPN, for example, needs one additional line:
socks-proxy 127.0.0.1 9050
Additionally, you have to exclude tor traffic from vpn, which will not be too easy, and there is plenty room for mistakes.
Actually, I don't see any advantage for you, using vpn over tor, as it might be very unstable and break when changing the exit node, which will happen from time to time.
But if you run tor over vpn, you have better protection againts dns leaks, or misconfigurated apps. Also, if the vpn connection breaks, there is still tor.