Controlling a stepper with one keypad-key

Hello there,

can you tell me, how it's possible
to turn a stepper motor by pressing key 1 on the keypad (4x4)
in the + Direction than stop after 50 Steps (for example)
and by pressing key 1 a second time
turn the stepper in - Direction and stop after 50 Steps?
Turn left and right is no problem for me in a loop, only contrilling with ONE key on the keypad...

Is this even possible?
Kind regards,
Chris

Edit
To do this by a servo motor is not a possibility for my project.