Sabertooth 2X32

Hello, I have got a Sabertooth 2x32 Controllers and am thinking of wiring it up to my wheelchair and to my RC receiver but I am not quite sure how I would go about it as I would like to still be able to charge the wheelchair battery using the onboard charger that come with the chair. I have attached a photo of the model of the chair. Hope you can help Thank you David Morris from the UK i have attached a photo Thank you