The simplest version of this is so rename it/ship it as the rROMAN graphics that the game currently uses, but if you are feeling more ambitious, you could also set it as the Mediterranean one and import the Civ3 info about which city graphics a civ should use.
As the second step of adding community graphics, the plan is to add Kyriakos's Persian set (https://forums.civfanatics.com/threads/five-culture-ancient-sets.629287/, third one down in the preview images).
The simplest version of this is so rename it/ship it as the rROMAN graphics that the game currently uses, but if you are feeling more ambitious, you could also set it as the Mediterranean one and import the Civ3 info about which city graphics a civ should use.