I actually like doing it but I have the same problem sometimes. I have gone as far as cutting tiny grooves or sanding the surface of hackle plyers to prevent it from slipping. For some of my larger salmon and steelhead jigs I will put 3-4 hackle in one jig.
I don't have that much trouble with them breaking when I tie them in narrow end first and wrap to the wider end. When grabbing the fine end it breaks off a lot.
Something else I have found that helps is to strip off one side of the hackle if it is stiff and then tie it in. This gives an almost flat surface to wrap and allows the feather to bend more than it tends to break.
I love taking my kids fishing, now if I could just manage to fish at the same time.