RX631 + GCC + r_flash_rx

I wanted to use the r_flash_rx API to reprogram internal flash of my RX631 controller.

Unfortunatley the support of the fit-modules for this controller ended with driver package 1.19 and there only the RX Compiler was supported.

Newer versions of the r_flash_rx API seem to support GCC but not for my controller.

Has anybody ported the lib to this controller? 

I want to try to add a target header for my controller(did not start yet). Would this be possible and just nobody did it yet or are there some blocking elemets i don't know of yet?