Find a wiring diagram of the Honda radio harness and/or a pin out diagram of the Honda stereo. If you can google this information then you will know which wires are used on the stock setup. Then reference the documentation of the new stereo to determine which connectors on the harness are used for volume control and splice accordingly. Note that I have not had to do this on my Pilot (LX with no stereo steering wheel controls) so I’m just suggesting what I would investigate.
Here you can input your Pilot details, the model of your new Head Unit, and it should give you all the details. Specifically which wires on which connectors from your car need to be used. Also when you get your Maestro module, you will need to hook it up to your PC via USB and use that website to flash proper firmware on the Maestro.
If your new head unit is iDataLink compatible, you can go for a more advanced model, Maestro RR, which will also connect to the Pilot's diagnostic port so you can get various vehicle info and diagnostics on your head unit screen.
Good thing about Maestro is if you upgrade the car and decide to use your new head unit in the new car, you can also reuse the Maestro - just need to re-flash the firmware.
You can also go to Crutchfield, enter your car model and head unit model, and they should list the compatible steering wheel control modules. Mind, when I upgraded radio in my '07 EX, I got an Axxess unit and had to go through a rather lengthy and fairly confusing procedure of programming each button. In my recent '13 EX audio upgrade, I used Maestro SW, and it was very much plug and play. Flash from website via USB, hook up per instructions, and all buttons work flawlessly.