take a look at Internationalizing Your Plugin codex entry to get a better understanding of WordPress Translations.
and read I18n for WordPress Developers after that you will know that if you coded your custom post types and metaboxes the right way with Translatable strings , all plugins work in the same way of looking for these strings.
and i would suggest using Codestyling Localization plugin which create a UI for translating plugins and themes inside WordPress admin.