Macbook Pro, bracket keys, brush size

Using a French keyboard, how can one access the bracket keys on a Macbook Pro in order to change brush sizes. The usual shift-option-( to get the bracket keys does not work, at least for me. I'm on 10.5.4. Thanks.

Under Edit – Keyboard Shortcuts – Tools You can enter a new key-combination for Decrease Brush Size and Increase Brush Size.

Thank you for responding. I had hoped to keep the usual key strokes so as not to confuse myself.