I found a possible way to use PS3 controllers with Epic. You will have to install a 3rd party application called ‘MotioninJoy’ which basically makes your PC see your DualShock 3 controller as an Xbox 360 controller. You can install from here: https://motioninjoyofficial.org/motioninjoy.
From what I read on their site, it’s just plug and play so you just install the application then plug in your controller.
Let me know if you run into any issues using this!