[Plugin: Multi-Column Taxonomy List] Limit by Hierarchy?

I was looking into doing something similar and added the get_categories attribute ‘parent’ to the plugin and it seems to have worked.

public function shortcode( $atts ){
		/* Extract shortcode attributes, set defaults */
		extract( shortcode_atts( array(
			'taxonomy' => 'category',
			'title' => 'Categories',
			'title_container' => 'h3',
			'columns' => '3',
			'orderby' => 'name',
			'order' => 'ASC',
			'show_count' => '0',
			'exclude' => '',
			'parent' => '',
			), $atts )
		);

		/* Build an array of arguments for the get_terms parameters */
		$args = array(
			'parent' => $parent,
			'orderby' => $orderby,
			'order' => $order,
			'show_count' => $show_count,
			'exclude' => $exclude
		);

Once added, I was able to use [mctl taxonomy=’category’ parent=’3′] to display only children of category 3.