What I suggest, assuming you run with Aali's driver:
In /Final Fantasy VII/mods, create a directory called <insert name here> (let's call it "modpath"), and a "field" subdirectory such as it's in /Final Fantasy VII/mods/modpath/field. Then, as I explained above, place the /colne_b1/ and /colne_b3/ folders in /mods/modpath/field/.
Then, modify ff7_opengl.cfg to authorize this mod:
mod_path = modpath.
This should enable you to use these fields without removing the old files.
If anybody has a better suggestion please go ahead.