Integrate gallery and gallery cms into existing cms

We have an existing client who's php/mySQL site is using a custom CMS. we need to integrate a gallery and lightbox into the existing cms and modify the site to show the new gallery. We need the development site corrected so that it works properly and so that once I copy it across to the live server that it will work there too. Relatively simple job - full source files, documentation and access will be given to the chosen provider.