In your X-Lite config, set the server address to x.x.x.x:5160. The port configuration on X-Lite is all about the incoming port for calls to the phone (which can easily by 5060). The two port settings (the one on the address and the one for the phone) are unrelated.
I'm not at a machine with X-Lite installed right this second, but there are a couple of places in the advanced settings that need to be tweaked to get this working.