IIRC, the mere fact of installing Hamachi takes care of getting through your 'doze (! - you're on your own if you've got that verk4kte Norton rubbish on your systems!) firewall. From there, once both machines are live on the 'net, you can ping the Hamachi IP addresses ('s freaky if you think about it, but it works..) - and if you can ping an address, you can load same into your RAdmin connect-to dialog.
Hell, if you wanna go the whole hog you can update your HOSTS file to map that Hamachi IP to a name..!