Hugh,
You're RIGHT. The pedal functions do not include the parameter to transpose up/down. Instead, you can store your transposition changes in individual Memory Registsration buttons and then use the foot pedal to trigger Memory Registration changes.
I like to use a Registration Memory Bank to store an individual song which may consist of a number of custom voice setups as well as a possible key modulation. I store each section of the song in individual Registration Memory buttons and then use the foot pedal controller (function>Regist Sequence) set to 'Regist+" to incrementally changes the settings (including transposition) as the song is played. - Scott