How do they assemble to the skate and pad? Are these meant to replace the laces?
These straps go through small tabs and pockets in the pad, and they are primarily used as leg straps and sometimes a boot strap. If it's used as a boot strap, then it goes from the pad, through either the center or rear holes in the skate cowling, and then back up to the buckle.
These straps won't replace the laces, which are almost always used to attach the toe of the skate to the bottom front of the pad. If you're looking to replace those, you'll want a product product similar to this (though we'll have to order the Reebok version for you):
Date published: 2012-10-02