How to create custom 41C modules from keystroke programs?

[Sylvain Cote]

(10-08-2020 03:08 AM)Gene Wrote:  Or go the HEPAX route. 4, 8 or 16K of ram from user programs would be available.

I thought of that, but the HEPAX RAM although externally compatible with the ROM format the internal structure is different and need the HEPAX ROM to interpret it correctly.
Dave question was "I have a clear use case for being able to create my own module ROM images to plug in" so HEPAX was rule out.