Step 1 - Check which ports Azureus uses to connect to the net. Tools>Options>Connection>Incoming TCP listen port
Step 2 - Configure the router to forward these ports. You will need to know the local IP of your dad's PC and the global IP of the router. Next consult the router help file on how to forward ports. Most probably you will use the NAT rule (Network address transalation) on those particular ports.
Step 3 - You might have to configure the local firewall (if any) to open these ports.
Step 2 is the hardest as this is a office comp, most probably the network admin won't allow you mess with the router. You may compromise the security of the network. (In Melbourne, Aus, a council worker lost her job at the Moreland city council when her 11yr old son did something similar.

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Try this with eDonkey first. If it works you will get a "Reachable" message at the bottom (status bar)
-Keith