contribution Employee made to 401 not corporation where does it go on the w2 and will it be taxed as excess contributions

Employees own a S corp they contributed to their 401k not the employer does it go on the w-2 and if so where  I can put the roth in box 12 coded as AA but what about the 401  employee contribution that just goes on  schedule 1 of their tax return correct and they are high wage earners so  they will be taxed  as excess contributions on the 1040