Setting up a Tekkit server alongside a Minecraft one

[quartz-1]

Newbie alert!

My nephew wants me to set up a Tekkit server for him. I'm already running a Minecraft server for him and he wants to keep that running. Platform is WSE 2012, with port redirection from my BT Homehub (single external IP address). How do I configure Tekkit so it can co-exist with the Minecraft server? Presumably I just need to get it to work on a different port. How do I do this? What issues is my nephew going to have connecting?

i'm sure this is a relatively simple query, but my Google-fu is weak.

[Maxis010]

In server.properties change the value of server-port of either server from 25565 to, for example, 25566

When your nephew connects to the server with the new port instead of just connecting to your address it's address:port

[quartz-1]

Trust me to miss the obvious!

Thank you.