initialization of EBR based ROM in Lattice MachXO2

I'm currently learning how to work with FPGAs. Currently, I'm working 
with a Lattice  MachXO2 family device. I implemented some logic and a 
CPU core.
In order to run a program on that core, I currently do these steps:
- (cross-)assemble the program on a pc
- convert the resulting binary to a .mem file (addressed hex)
- I let Lattice diamond IPexpress regenerate the ROM using that .mem 
file
- I restart the whole tool chain to generate a .jed file (takes 5 to 45 
min)

in IPexpress, I checked the option "allow update of inititialization 
file stored in UFM"

What I want to do is to generate new initialization data from a new .mem 
file and either combine it with the existing logic configuraton into a 
new .jed file. Or, generate a .jed file to program only the UFM part.

I can write UFM pages.

What I cannot do is convert a .mem file to the apropriate pattern of 0s 
and 1s the .jed file is made of.
I could not find a tool for that.
I can find where the initialization data starts in the .jed file
But I cannot figure out how the data from the .mem file is converted to 
the 0s and 1s in the .jed file.

I shall appreciate any help or hints