This one is a really easy mod; it’s much easier than the previous dedicated scene select mod. The Line6 M-series are all capable of using an expression pedal to change parameters within a given model. Things like delay rate, mix level, tones, pretty much any parameter can be adjusted on the fly using Line6’s expression pedal or any expression pedal that uses a 10k linear potentiometer (so, Ernie Ball VP, VP Jr. are out, as are standard Mission Engineering pedals.) The Line 6 expression pedal is quite simple, using only a 10k potentiometer between the tip and sleeve of a regular 1/4″ connector. When the potentiometer is all the way “up” then you can set the maximum parameter value, when it’s all the way “down” you can set the minimum value. This video shows you how to set these (and happens to use a knob as well).