It’s possible to do this on a PC providing the game you’re playing supports inputs from multiple controllers (most modern sim racing titles do). Just connect the pedals as well as your wheel and then make sure that you've configured the pedals for the gas, brake, and clutch functions in the game that you’re playing, using its control settings screen.
On a console, it is not currently possible to use the PRO Racing Pedals with older wheels due to console architecture that requires all of the inputs to be part of one peripheral.