You can use hooks to modify or add things to specific blocks. Here are some pin board specific hooks.
headway_before_pin_thumbnail
headway_after_pin_thumbnail
headway_before_pin_meta
headway_after_pin_meta
headway_before_pin_content
headway_after_pin_content
headway_before_pin_board_pagination
headway_after_pin_board_pagination
Please see our Hook Reference for more on how to use these
