Introducing Maple as Honey: The Omega MSX FlashROM Tool:
https://github.com/lfantoniosi/oflash
Right now I only support MX29F040 but I pretend adding SST39 as well (as soon I get one).
The Omega ROM is not your ordinary megarom mapper, instead the SPLDs splits the 256KB bank of the ROM linearly across 4 64KB slots being: 0, 3.0, 3.1 and 3.3. And to make things even more challenging the memory mapper sits at slot 3.2.
The tool needs to sweep the entire 4 slots from 0x000 to 0xfffe (can't write the last byte in an expanded slot) while issuing commands to specific ROM addresses.
Here is the video it takes roughly 5 minutes to flash the 256KB. There is a lot of bank switching while the entire BIOS is being scrapped and the program must run on its own.
And the good thing is that since I use sector erasing you write a 256KB bank while preserving the other one. And it is safe to switch the banks when the tool asks for button.