You could use the Multiuser Xtra in peer-to-peer mode - one machine operating as the server and the other as the client. However, there is a steep learning curve for someone who has never used this xtra before.
There are pre-built behaviors for the multiuser xtra in the Library. I have never used them but I have created my own parent script that makes connecting Director movies simple. Let me know if you are interested and I will send it to you.