First you need to get a telnet Communication Toolbox tool to connect to the server.
The best is free, called TGE TCP Tool, and is available on my web site...
ftp://ftp.aprs.net/pub/
Place TGE TCP Tool in the extensions folder on your Macintosh, and run MacAPRS.
You must now configure the program to use the new tool correctly.
Choose Settings/Communications/TNC via TCP. Enter the following information into the appropriate fields in the dialog box:
To connect to the server, select Settings/Open TCP via TCP
The stations will flood in. If you want to disable the sound temporarily, press the Caps Lock key.