@motorollin
I agree, if you can, do a tutorial! and what hardware is needed, eg. chip types. Adding in newer libraries to essentially a startup sequence that would get loaded anyway by a re-boot can't be against copyrights, esp if you own the ROMS to begin with. It would be like making a copy of the AMIGA OS 3.9 CD, including some new libraries and using that to re-install instead of your original one. It's just a backup from a ROM chip instead of a CD. Like a USB stick would be.
Please make a full step tutorial. If in doubt, could always ask AMIGA if it's ok to do it if you OWN the ROM in the first place. Pretty sure you're allowed to make a copy if you own it. Not sure about the adding in library bit...who knows I see no harm, beats having to re-boot.