need help adding a metabox to select gallery

I was using http://www.advancedcustomfields.com/ and http://wordpress.org/extend/plugins/advanced-custom-fields-nextgen-gallery-field-add-on/ to add a metabox that allows the admin to select a gallery for a particular page. However, I’ve upgraded NexGen Gallery and ACF to the latest versions, and it broke the site, producing a PHP error where the gallery is supposed to display. It looks like the add-on ACF for NextGen hasn’t been upgraded in a year. Can someone provide the code to skip over using the ACF and ACF add-on plugin to just add a metabox via the functions.php file? I am not a developer so would really appreciate some help.

http://wordpress.org/plugins/nextgen-gallery/