Hello rushin thakkar,
That documents explains how to implement a custom service on KW40Z. It should be very similar for KW41Z.
Can you tell me on which step do you need help?
Also, please refer to the "BLE Application Developer's Guide.pdf" document located in <SDK path>\docs\wireless\Bluetooth for information on how to integrate the NXP stack in a BLE application.
Regards,
Gerardo