To program it with the valet switch do the followin,
Open the drivers door.
Turn the ignition to the on position (not run) then back off
Withing 5 Sec. hold the valet switch in, the siren should chirp once, release the button and hold it in again, the siren should chirp 2 times, release the button and hold it one more time the siren should chirp 3 times. This means you've accessed Menu #3 (which is in the install manual)
http://www.directed.com/guides/manuals/ig/clifford/N919564_6-03.pdf
Release the valet switch and close the door to save the settings.