http://www.musiciansfriend.com/amplifiers-effects/fender-1-button-footswitch-for-mustang-and-blues-junior-amps?cntry=us&source=3WWRWXGP&gclid=CO28iaTa0MICFSwV7AodOXgAUw&kwid=productads-plaid^80506347987-sku^H70561000001000@ADL4MF-adType^PLA-device^c-adid^51870555867
As far as the clean setting goes, i think the 57 Deluxe is a good one to start with. But what you should do is go up to where the light is green and that's where you can save your own preset on any of them. You have to adjust each knob to where you want it, and turn the effect knobs up and then all the way down. I don't know if you've seen this yet:
http://support.fender.com/manuals/guitar_amplifiers/MustangI-V_%28v.2%29_advanced_manual_revA_English.pdf
~Rusty
