Why would you want to? Save the farewells for those worthy of the effort. Any arrogant or egotistical person won't really appreciate it anyway.
If he is your employee, as in: he works for you, be very careful what you do, you don't want to seem as if you are rewarding his attitude in front of other employees. I would recommend something as minimal as possible and only dictated by custom.
A firm handshake and a nod is about all I personally could manage for someone like that.