Use the following form (G-1145) if you desire to have the USCIS notify you 24 hours after your application is accepted at one of the three lockbox locations.
http://www.uscis.gov/USCIS/Services%20&%20Benefits/Immigration%20Forms/G-1145.pdf
http://www.uscis.gov/USCIS/Services%20&%20Benefits/Immigration%20Forms/G-1145.pdf