Hello Sean,
The FRDM projects are very similar to the TWR projects, as you can see in the SCH files, most of the pins are compatible between the FRDM and TWR functionality. You could easily adapt the FRDM project (or any other) to the TWR project looking at the board files. (board.c/h, gpio_pins.c/h, hardware_init.c, pin_mux.c/h)
See: C:\<Project path>\boards\frdmkw24\wireless_examples\thread\router_eligible_device\freertos\
-JC