If available, you can use a cable machine for this exercise.
Alternatively, fix a resistance band to a solid object at footrest height.
Sit in your wheelchair with the resistance band in front of you.
Place your feet on the footrests, and ensure your brakes are applied.
Hold one end of the resistance band in each hand at footrest height with your elbows straight.
Pick up the slack in the resistance band by wrapping it around your hands.
When ready, pull through the resistance of the band leading with your elbows and pinch your shoulder blades together.
You should finish this movement with your elbows high and your hands against your chest.
Return to the start position, and repeat.