You need a DC PM motor to turn the potentiometer. You need a gearing mechanism to reduce the RPM, an a sip clutch (so the motor doesn't brak the potentiometer at its limits, plus you can manually operate the potentiometer.
The motor will be controlled by an H-bridge, which has two logic lines, a CW and a CCW.
As for the remote, that is a little more open.
You can find/build a transmitter/receiver set that provides the logic to provide the signals you need (can't recommend one though, at least one in production).
You can use an existing remote (or chip, or code in a universal remote), and build a microcontroller based decoder for it (takes software skills).
When I built my A/V switcher, I chose the former, as the logic with a decoder chip was easier for me than the software code would be. I salvaged the decoder chip from some obsolete gear, and "emulated" the original remote in a programmable universal remote (One ForAll URC
You should ask in the sci.electronics.design group.
Maybe salvage the remote, reciever, and motors from a cheap RC car that has at least 2 different control axis like front/back or forward/turn, you get the idea. By doing this you won't have to do much more than making everything attach to your volume control.
NO, no...salvage the entire motorized volume control from one of the plethora of Technics receivers which are dustbinned daily because the output chips have blown...and for which replacements are too expensive to economically fix. Possibly some of those units have the remote receiver/decoder on a separate board as well.....
Possibly could be a stretch. Not knowing the details of the Technics design:
On my Yamaha, on the main system board, near the front, is the system controller, which, amongst other things, decodes the remote commands (in software), an provides logic to control its volume motor, source selectors, drive the LCD, and tune the tuner.
On Pioneer here: The remote and front panel is decoded in the front panel, which sends logic signasl to the various pieces, including the DSP.
I would think it would be just as easy to start from square one with new silicon (EG a micro or a specific remote decoder chip)