3x4*5 microbuttons pads & Arduino (Mega2560R3) = 60 DCS USB buttons?

These (Ebay US $1.86) 4x4 + 4xtra buttons (+8 led’s) microbutton pads are possibly suited to be made in MDI buttons (landscape 4rows x5buttons),

3 of these make 3*20 = 60 buttons

https://alexnld.com/product/8-led-4-x-4-push-buttons-matrix-keypad-16-key-switch-keyboard-for-arduino-avr-arm-stm32

https://www.ebay.com/itm/4x4-Keypad-Matrix-Keyboard-Module-16-Buttons-Mcu-LED-For-Arduino-DIY-Smart-Car/201967003312?var=501979887449

So, I could buy 3 = 60 buttons, an Arduino (Mega2560R3), and with an adjusted (Linux?) “256 joystick button” Arduino sketch I can plug an Arduino USB in, and have 60 additional button in DCS?

Errr, how could that be accomplished, could anyone explain how to go about this in somewhat kindergarten English?

- I can solder and copy paste Arduino .ino in the IDE and made the USB interface for a Logitech race wheel shifter

- I am on a Windows PC

source “256 button” Arduino sketch:

https://forums.eagle.ru/showpost.php?p=4048843&postcount=254

A good starting point:

https://forums.eagle.ru/showthread.php?t=117011&highlight=overpro

Shoudn't be a big problem to connect the matrix-wires correctly.

But that's "only" the input-part.

Output is another story...