ELWOOD - Education officials voted yesterday to change state special education requirements, a decision possibly affecting thousands of students across Long Island. The proposal calls for several cost-saving measures, including the elimination of a mandate that school psychologists help evaluate special-needs students. Lawmakers have not said how much the cuts would save, but local school officials say there would be no financial benefit. "It jeopardizes the protections and services for kids," says Dr. John Kelly, a Commack High School psychologist. Some parents say their children are progressing fine under the current system, and that rule changes could hinder their progress. The state legislature is expected to vote on the changes in the coming weeks.