When trying to find ways and means to put our custom compilation inside the flash, I bumped into this very recent article (it is in Russian - you need a Google Translate) explaining about the dumping and the flashing process of the chip inside.
Also, the author documented the rest of the process in the Github (it is in Russian too - Google Translate works on it) - it is an extremely good read.
The method would help me to dump and flash the ROM faster, and also to help me understand that program inside better.
From the article, the pictures are the attempts to build a makeshift "cartridge" that holds that flash board and the "slot" connected to the SUP console:
On that, I will try to build this too and experiment it! :)