[Plugin: WP-LESS] how to set WP_DEBUG?

how specifically does one set WP_DEBUG? Alternatively, where does one use: $WPLessPlugin->processStylesheets(TRUE);

This doesn’t work, for example:

require( get_template_directory() . '/inc/wp-less/bootstrap-for-theme.php' );
$WPLessPlugin->getConfiguration()->setUploadUrl( get_template_directory_uri());
$WPLessPlugin->getConfiguration()->setUploadDir( get_template_directory());
$WPLessPlugin->processStylesheets(TRUE); // force re-compile of all files?
$WPLessPlugin->dispatch();

Help? Thanks! -Paul

http://wordpress.org/extend/plugins/wp-less/