How to create a theme specific translation of buddypress? [closed]

Question

Originally asked on the BuddyPress forums:

For distribution purposes I would like to include my customized buddypress language files in my theme alongside my other language files. No matter what I try though I can only get the language files to display if I copy them over to wp-content/languages as described in the buddypress codex. I thought that the following would work, but it doesn’t:

function load_buddypress_language_files() {
    load_theme_textdomain('buddypress', get_template_directory() . '/lang');
}
add_action('plugins_loaded', 'load_buddypress_language_files');

This is possible isn't it?

WP: 3.5.1 BP: 1.7.2