You could wire aftermarket lights with an aftermarket harness, however if you have the OEM harness (and therefore the OEM button) it is pretty easy to wire hella lights into the OEM harness. No splicing, you'd just need to feed the wires from the hella lights into connectors that match what's on the OEM harness
There are a couple holes on the back of the protection bar with threads (either 8 or 10 mm, I forget) which you could use to mount lights, but I'm not sure how strong this would be, considering the OEM lights are supported by stands that are mounted directly to the metal bumper.
It would be expensive just to use the OEM harness and mounting bracket to swap out those lights for hellas, but maybe worth it...