The easiest way would be to use flight phases and make the button activate phase 4 (the master phase), you can then trim it for launch settings, when you release the button it will go to flight phase 1,2 or 3 depending where the 3 position switch assigned to these flight phases is.
The other way would be to make up mixers, in the define mixer menu, for each control and have a line with a fixed value which is activated by button M, so when the button is pressed this is added to the control inputs to give you the offsets you want. You can then adjust the values in each mixer until you get the desired effect, or use digiadjusters on two of them to save going into the mixer to make adjustments