To use focus peaking and the 4x (or 2x) MF assist:
Press the Menu button
> move to the "camera" 1 options
> scroll down to the Focus Settings (press ok)
>Set Focus Method to MF
>Set MF Assist to 4x (or 2x)
>Set Focus Peaking to ON
Now, when you mount a non-Q lens (with a dumb adapter), you will be able to use the focus peaking - it will work without any other button press. To see a 4x (or 2x if that's what you set up) crop, to assist manual focus, just press the "OK" button. These two features really help with manual focus using the Q and a third party lens.