A cover letter for a promotion should be done on personalized stationery and should be polite and professional. If you are requesting a promotion you should state why you feel that you're deserving of a promotion and what your strengths are. You should mention contributions that you've made to the company and projects that you've successfully completed. You can say that the salary is negotiable
. because you don't want to be turned down for asking for too much of a raise. Address the cover letter for a promotion to your immediate supervisor and CC it to any other people in management that have decision making powers. For more info about cover letters for a promotion you can visit http://tinyurl.com/n9n44a.