Hi caiot5,
If you could make it work with Debian on x86 in a similar way, I’m sure it would be doable with OpenWRT. You wouldn’t even need a working/bootable OpenWRT kernel, since you’d be running RouterOS…you would just need the OpenWRT userland to live on the second partition.
I have no interest in working on this, though, so best of luck if you do, and perhaps you could come back and let us all know how you fared if you are successful. 
The other thing to consider is that the most recent versions of RouterOS (6.4x) have changed how to enable devel-login, and it is no longer as easy to do as before. It also won’t survive OS upgrades…you will have to re-implement it after every upgrade.
– Nathan