You could try making a copy of all the files in the mod and giving them a different name but there is no guarantee it would work. Replace models like the one you linked are usually made to replace a specific vehicle. Then you've got the Sheriff models, sheriff and sheriff2. police2, police3, police4, policeold1, policeold2. However, there are many police models in the game that don't use that model name. That mod has model files called police.yft, so it will replace any in-game vehicles that use that model name.
