Do you mean that you would like the aftermarket levers to work as a safety, and not just a decocker? If the levers don't have a place for the little ball bearing and its spring, they won't remain in the down position - so I think you would need to check with the manufacturer of the levers whether or not they would work for your application.
As for the actual process of changing the levers, if you've seen videos on the decocker modification you've seen a video on how to remove and reinstall the safety levers.
It really is a simple process of moving the safety lever so the pin is exposed, driving out the pin, removing the safety levers, assembly is in reverse order. Just make sure the little spring ends up in its proper place during assembly.