All of the honda accords of the same years have the same engines regardless of whether the car is an EX, LX, SE or DX trim level. The trim level just refers to the options on the car. The SE is usually an LX with some added options.
if you're buying spark plugs all the store will need to know is the year of the car and whether the engine is a 4 cylinder engine or a 6 cylinder.
hope that helps