How does picking up the Way of the Shackled Beast style effect a character who is already a Monk?
You would probably have to go through a period of retraining, if your DM allows it. Check the back of the PH II if you've got it. Essentially, each level you gain you choose one previous class feature, one feat, or up to 4 ranks out of one skill and swap them over for something equivalent that you could have also taken at that level.