2wire xp remote desktop

We have a 2wire 1000HW router with a 4 computer LAN at the office. We would like to set up the router firewall so that two different office members can access their own work cpomputers from their house. At the present time we are able to set up one user to properly access their work computer from their house using the XP remote in the firewall setting. However when trying to give xp remote privilage to the second computer, it is declined by the 2wire administrator stating that the xp remote is already assigned to the first computer. Is it possible to set up a fire wall and allow two different office members to access their work computer form theis home? If so how can this be accomplished?