As far as i know, LANC only specifies the signals to be sent between the equipment. It doesn't specify the physical connection. I've seen mini-DIN, 3/32" TSR, and something like mini-Svideo connectors used. It shouldn't require anything more than the right adapter plug or cable.
OK you want to go the other way around. That would be much harder as you'd need a 10 pin A/V socket for your existing controller to plug into. From that you could then connect to a 2.5mm plug with the appropriate connections. The problem is I know of no source ot the 10 pin socket apart from a dead camera,
The other issue if my memory serves me well is Canon and Sony's interpretation of the LANC protocol seems to differ a bit. Even if you could make the electrical connections it may not work or work as expected. If you can afford it, might be better to buy a generic LANC controller that's guaranteed to work with your Canon camera.