Compute radial mode frequencies with GYRE and put them in MESA history output.
The "magic" happens in src/run_star_extras.f90, which calls GYRE with the supplied gyre.in inlist to compute radial modes, and then stores them in the LOGS/history.data output.
It only happens if the &control parameter x_logical_ctrl(1) = .true. is set, as in the provided inlist.
You may need to adjust some things in the GYRE inlist to your needs, such as the frequency scan range or the numerical scheme, but probably it's plug-and-play for most applications.
Based on this tutorial for the MESA Summer School.