Training your pup to tree a squirrel in just the right way can be quite challenging. Especially if you have very little experience in training dogs. While you could buy a dog that has been professionally trained or pay to have someone train your pup, what's the fun in that? You can start the process almost the day you bring your pup home, and the sooner you start the better.
The big thing is that puppies love to play chase, which if you get right down to it, is pretty much what treeing a squirrel is all about to your pup. No matter what age your pup is when you start training him to hunt virtually anything, you need to also make sure he has been trained to ignore the sound of gunfire up close and at a distance.
The task at hand is to train your dog to find squirrels and chase them up a tree where it will be easier for you to shoot them. There are, of course, many different methods to do so, but each has the same end result. Your pup will also need to either be learning the basic commands ('sit', 'stay', 'come', 'down') during his hunting training or have already mastered them. This is all about your pup doing what you have trained him to do while still seeing you as the alpha pack leader.
You will also need to decide on a command word you are going to use to tell your pup to hunt squirrels. The simpler the better, you could simply say "squirrel" or "hunt." It really doesn't matter what you use as long as you use the same word every time. Your pup needs to know what is expected of him when you give him this command word.
Depending on the age of your pup, you may be able to combine basic command training along with your hunting training or you can always do it once your pup has completed "Basic Training." Also, your pup will need to be trained not to be gun shy. Beyond this, there are a few things you will need to make the training easier. These include:
The biggest things you can bring to each training session are a happy fun attitude and plenty of patience. You will also need an area with plenty of trees and squirrels as a training ground for your pup.