log into the firewall, if ur admin you should be able to do this... same concept as logging into your router at home. Setups are somewhat different, but look for a " Port Forwarding" section. Designate whatever your machine IP. ie 192.168.1.100 would be something youd see at home, forward the range ( 6881 to 6889 like e said) to your your ip.
How do I find out what my machine IP is to the outside world? I have an IP of 10.5.1.58, but as far as I understand that is only for within my network
In your router, forward a port to the internal IP address of the machine you want to use BT on. Sounds like 10.5.1.58 to me.