This module is designed it so that if you install the appropriate PECL module, nothing changes except that stuff gets faster. That's an approach we are using throughout core: Model on a PECL. That provides a known, non-Drupal-specific API (easier for new people coming to Drupal) as well as a very easy way for Sites With Root(tm) to speed up their Drupal site.

If you want to declare your own class adapter to make it working with PHP OAuth library or any implementation you want, simply implements the DrupalOAuthConsumer interface and you’re done.

<?php
class MyOAuthAdapter implements DrupalOAuthConsumer {

}
?>

More information about the interface can be found here: http://fr.php.net/manual/en/class.oauth.php