This is how you add the pins and wires for the steering wheel controls.
This guy added two wires which control all 5 functions (dont know how) my logic was you need 3 wires which can make 8 combinations (000,001,010,011,100,101,110,111) which are sufficient.
2 wires would make only 4 combinations (00,01,10,11)
But any how this video will show you how to add the wires and any good electrician who has done this before will know which pins are used and in this video the head unit used had combined plug which had the steering wheel pins inside it so he added them to the plug too.
For Grande infotainment system they are separate so easy to connect . No idea about civic oem system but electrician will know
I can refer you to electrician in Islamabad. Sarmad Motorpsorts (f-7 i think ) they have an electrician who will be able to do it but call them and ask to be sure