Multiple tiny_mce instances, hyperlink issues

I have multiple tiny_mce instances on a metabox in the media-upload.php page.
This works fine and displays / saves text fine by calling:

wp_tiny_mce(true,
	array(
    	"editor_selector" => "my_text_box"
  	)
);

The problem is that the hyperlink pop box doesn’t link correctly. The box pops up ok, but then when you click ‘add link’ the whole page refreshes.

I think it’s down to the tiny_mce not targetting the text box because there are multiple instances of it.

So I tried this method:

// important: note the priority of 99, the js needs to be placed after tinymce loads
add_action('admin_print_footer_scripts','my_admin_print_footer_scripts',99);
function my_admin_print_footer_scripts() {
	?><script type="text/javascript">/* <![CDATA[ */
		jQuery(function($)
		{
			var i=1;
			$('.my_text_box textarea').each(function(e)
			{
				var id = $(this).attr('id');

				if (!id)
				{
					id = 'my_text_box-' + i++;
					$(this).attr('id',id);
				}

				tinyMCE.execCommand('mceAddControl', false, id);

			});
		});
	/* ]]> */</script><?php
}

But that doesn’t load any tiny_mce onto any of the boxes.
Any help or ideas?