Basilisk II - serial port?

[ururk]

I'm having trouble getting a virutal serial port to show up under Basilisk II

Host: OS X Sonoma
ROM: Quadra 900
CPU: 68040

On my host, if I create a serial port:

socat -d -d pty,rawer,echo=0,ispeed=1200,ospeed=1200 pty,rawer,echo=0,ispeed=1200,ospeed=1200
2024/01/03 18:11:13 socat[24586] N PTY is /dev/ttys008
2024/01/03 18:11:13 socat[24586] N PTY is /dev/ttys009
2024/01/03 18:11:13 socat[24586] N starting data transfer loop with FDs [5,5] and [7,7]

I've added /dev/ttys008 it to Modem Port or Printer Port (in Basilisk II GUI), but nothing shows up in system 7. Do I need to install an extension in OS 7? Or am I missing something?