You want to use the M3's EXTERNAL control surface (the 8 switches, 8 sliders, and 8 pads) to control functions in your external sequencer.
For example, in Ableton Live you can use Instant Assignment to assign a physical controller to any function in Ableton Live. You go into a special assigment mode, select the sequencer function you want to assign to an external control surface, and then move a slider or switch or pad on the M3 to complete the assignment. You could use this technique to quickly assign the 8 pads to the triggers in an Ableton Live drum rack.
Note: it's a good idea to use CC numbers for the control surface that are not used by any other function in the M3.
A contiguous block of CC numbers from 39-63 are completely unused by any M3 functionality. These numbers are perfect for assignment to the sliders, switches, and pads when the M3's control surface is in EXTERNAL mode.
- In Global mode, go to page P1 MIDI.
- On the Ext.1 tab, touch the > icon and select the first unused external setup (probably setup 102). This will result in Off assigments to all the sliders and switches shown on this tab.
- Assign CC numbers 39-46 to the switches, and 47-54 to the sliders.
- On the Ext.2 tab, assign CC numbers 55-62 to the pads.
- From the page menu, select Rename External Setup and give your assignment a meaningful name.
- From the page menu, select Write Global Setting to save these new assigments to your default (power-on) Global settings.
If you don't want these to be default settings in your M3, you can save a special PCG file named something like "Ableton" or "Live" that contains only your global settings. Then whenever you work with Live, just load that PCG file in the M3 and you're ready to go.