The only problem is unscrewing the collar that's inside the front of the hand grip.
This requires a special tool to remove the collar, then the hand grip simply slides off, and the new one on. The collar is reinstalled and snugged down tight.
While I don't recommend this, some people have used the gun's slide as a tool to unscrew the collar. The slide is the plate that fits under the bolt.
DON'T follow advice to use a pair of needle nose pliers to unscrew it. One slip and you'll damage or ruin the thin action bar tube.
You can buy a special wrench to do this.
http://www.midwayusa.com/viewproduct...tnumber=723227
You can also make a tool with some 1/8" steel plate.