Yes, you can do it your self, not easy, but doable. Feed your tort on a piece of flat stone or ruff tile. It will help file the beak and keep it filed down. YvonneG I believe has a thread on how to trim a beak. I would try feeding him on the rock/tile for a while and see if that does it. Also, a reptile vet can do it for you.
I don't recommend that a person does this the first time. I think you should go to your vet and ask him to show you how to do it. Then if it ever needs trimmed again, you can do it. There are blood vessels in the beak and it would be very painful to the tortoise if you do it wrong.