Hey Rick - great question!

Most tuners do not have a setting for 1/2 step down. Simply do this:

Tune the low E string 1/2 step lower to Eb (your tuner may display D# which is the exact same note)
Tune the A string to Ab (or G#)
Tune the D string to Dd (or C#)
Tune the G string to Gb (or F#)
Tune the B string to Bb (or A#)
Tune the high E string to Eb (or D#)

Now to get it into dropped D, tune the low string down 1 full step further from Eb to Db (your tuner may display C# which is the exact same note)

Hope this helps!

Mike