As I know mc could not use specific port, but you can cheat it. It is Linux, isn't it?
As mc uses system ssh, you need to work with ssh, not with mc.
Go to /home/user/.ssh/ and create there file "config" if not existed. Then write there specific section for each host you work with regulary:
host vistafail
user root
hostname vistaepicfail.microsoft.com
port 6666
Now you could connect to host
[user@localhost]#ssh vistafail
ssh will do other work - ssh
root@vistaepicfail.microsoft.com -p 6666, the same in mc - open shell link and enter "vistafail"
I am not sure if such host existed, but method works