Hola Dan,
The configuration you are asking about is not something that you would need to set on your Mitel Server, in fact those specific environment settings are for MS Windows/DOS based operating systems.
No worry though, the settings you are being asked to make is common for Foxpro based applications. However, those setting are only required on the client systems (the workstations running the application), and not the server (your Mitel box). While the data for your Foxpro application can be stored on your server, the application itself only runs on the workstations. You should have no trouble with it.
Have fun.
R.