If you are having trouble typing in the '/c blah' in the chat box, try the console one, open console and do 'connect("ip",port)'
So if you wanted to connect to 12.13.14.15 (made up), you would type 'connect("12.13.14.15",3000)' in the full console(~), without the ' but with " around the ip.
I'm not sure what else you are doing wrong, you do actually have a partner to connect to? You both installed hamachi and joined a network, and used that ip?
on the same network?
You can use LAN addresses and that will work just as good, if not better, you don't need hamachi for local.
Still not sure how you can have so much trouble... firewall or anti-virus maybe?