Below you can see the pinout drawing of that 24-step, 9mm mouse scroll wheel rotary encoder. As shown above, the rotary encoder has two data pins (A-B) and a common pin (C). Basically a rotary encoder ...

Rotary encoder pinout and wiring. Most RTs also has built in ‘push-on’ momentary switch, usually one side has 3-pins (two coding pins and one common/ground pin) and the other side has 2-pins (N/O ...

Disassembling the mouse you can get two optical encoders plus four infrared emitter/detector pairs. Then you can reassemble your new sensors into a quadrature incremental optical encoder.