I am not as proficient as Nick or Kasra at EVO programming, but I really wanted the "preset" on M also. I just used the template to make a new assignment for a special model type. I had to do this because I also use M as my master/slave switch on the trainer cord. ANYWAY, it works, and is easy to program as a momentary switch. That leaves M free for BASIC and DELTA to be my trainer cutoff switch.
It is also possible to put a MIXER that includes M and one of the flight phase switches together such that the 3 position flight phase over-rides the M momentary switch. This would allow me to have DLG and trainer both working with the M switch during the same flight (but you would have to leave the preset mode before going to trainer - which makes sense anyway). Now that I have "unlearned Asian Radios", it is fairly straightforward to do all these things. The big problem for me is remembering which menu has which function assigned to it ("where is ATV defined? where do I invert a servo? etc..)
Joedy made a nice "cheat sheet" in one of the MPX threads that lists what "Asian Radio" function is found on which menu.....now all I have to do is memory it. LOL.