I have no help for the XD, but I installed a set of night sights on a G33 a dozen years or so back.
It was pretty straight forward but (like almost ANY job) you do need the right tools. The front blade was/is held in place by a small hex head screw. You can likely buy a nutdriver to fit it; I made one from a metric socket head screw (4mm or 5mm socket, I forget which... ) threaded into a piece of hex aluminum. If you have access to a lathe, it's a pretty easy job.
The rear sight can be pressed out or tapped out with a pin punch & a small hammer.