You use the World Map to setup your IFR flight plan, load C&D into the aircraft, power up aircraft/avionics, open the ATC window and you see a choice for “Tune RCO/GCO name on frequency”. Since I am at KPRB, here in Paso Robles, California, my local is Hawthorne on 122.400.
Tune that or use the ATC window choice and you get:
Select #2, and when prompted to Read Back do so, and you get:
You are now cleared for IFR for 30 minutes. After takeoff, you tune to the assigned Departure frequency and establish normal contact and away you go.
What’s also cool is, if you exceed the 30 minutes before contacting Departure, IFR will be canceled and you will be informed as such when you contact Departure after takeoff, at which point you can refile.
I’ve been doing this in 2020, since I first got the sim, it should also be an option in 2024.