WHEN COMMUNITY RESIDENTS oppose a large institution whose expansion threatens their homes or businesses, the people must "fight rough, fight tough and fight for keeps, "William Worthy, author of "The Rape of Our Neighborhoods, "said last night.

Speaking before a group of 30 students at Phillips Brooks House, Worthy talked about his 1969 fight against a New York hospital that planned to tear down the apartment building where he lived in orde to build a parking lot. Worthy described his methods for organizing the neighborhood residents and attracting widespread publicity for the tenants' cause.

Worthy said hospital officials tried to force the tenants out of the building by turning off their heat and allowing a large German shepherd to wander in the hallways. Calling such actions "institutional imperialism," he said more people should organize and fight in similar situations