Connect to SQL Server Management Studio over VPN (Hamachi)
Have you allowed remote connections in Surface Area Configuration -> Services and Connections -> Remote Connections?

I haven't specifically tried recently, but I have enabled TCP &amp; Named pipes. You can also force a protocol if you need to, e.g. in the server name, use NP:myserver in order to force named pipes, or TCP:myserver in order to force TCP. 

Try enabling named pipes in the connection setup too - client and server.

Also, hamachi normally uses its own IP range, so you should check that you can actually telnet to port 1433 of your server.