This is not culture but religion. No, there is no way (I would know of) to change the religion of a single settlement. You can only do so for the entire faction:
Code:
Identifier: set_religion
Parameters: faction, religion
Description: Changes the religion of a faction.
Sample use: set_religion England pagan
Class: SET_RELIGION
Identifier: change_population_religion
Parameters: faction, religion_to, percent, religion_from (religion_from optional, current faction religion by default)
Description: Changes the religion of a faction.
Sample use: change_population_religion England pagan 50 catholic
Class: CHANGE_POPULATION_RELIGION