It's hard to tell from the website exactly what it does and how, but if it is acts as a local DNS server that queries OpenDNS DNS servers and encrypts everything going to/from them (my assumption), it would probably work with Tunnelblick, More to the point, it would work with OpenVPN; Tunnelblick probably doesn't have anything to do with it. The only catch I can think of is that flushing the DNS cache wouldn't flush the DNSCrypt cache (if there is one).
However, the only thing it accomplishes (assuming you are using a VPN for all traffic) is to hide your DNS queries and responses from your VPN server (they are already hidden from everyone else because they go through the VPN). If you trust your VPN server that shouldn't be necessary; if you don't trust your VPN server you have bigger problems.