getting the factory sights off is usually the hard part. everybody has their own way of doing things, I find a hammer and a sturdy punch work best with the slide held firmly in a vise (soft jaws or leather lined). care must be taken not to scratch the slide, tape comes in handy. getting the new sights in is a bit easier but they may need to be relieved a bit before they go in, care must be taken because if you take to much off the sight will not stay in position and unless you know some old gunsmith tricks you'll have to purchase new sights. you must be careful with the front sight as it is very easy to snap the sight off the dovetail or if you get to rough with night sights you can cause the tritium vile to break. the install is where the sight pusher is really needed, it allows fine adjustment of the sights. most sight pushers are not built strong enough to remove the factory sights, many sights tools have been broken attempting to remove xd sights.
I highly recommend paying the $30 or so to have a professional do it for you.