PS/2 devices are powered by 5V and use two data pins to communicate back and forth. There's tons of example code out there for every kind of microcontoller (including Arduinos) for keyboard and mouse interfacing. 

So all you need to do is connect from the PS/2 plug to your breadboard. Unfortunately, these plugs are not breadboard friendly. That's why you need this connector. It is easy to panel mount, and has pre-soldered wires connected to the 6 contacts (of which 4 are used). 

For PS/2 devices

• Green wire is +5V
• Black wire is Ground
• Brown wire is Data
• Yellow wire is Clock
• White wire is sometimes Mouse Data for 2-in-1 splitter cables
• Red wire is sometimes Mouse Clock for 2-in-1 splitter cables