babylonian Spears

[MarcusAureliusAntoninus]

Ok...

Open the export_descr_units.txt, find Babylonian Heavy Infantry (unit #295). One line that says:

ownership        slave, parthia, romans_julii

make is say:

ownership        slave, parthia, romans_julii, saba

Since the unit is using the merc trick, I don't think you need to worry about any of the other unit files. (Though if you get a crash when using them in game, I was wrong.)
Now go to the export_descr_buildings.txt, look for the second on 'MIC L'. Look for "royal_barracks_L1", and go to the very bottom of that section. You will know you are at the bottom when you reach the entry for "building barracks" (no letter and the buildings have no recruitment or bonuses). On the end of the list (above, in royal_barracks_L1), place this line:

                recruit "eastern infantry babylonian heavy infantry" 0 requires factions { saba, }

They will now be recruitable to Saba everywhere, in the highest level of saba barracks.