Hi all,
I found it:
echo JCckDev::renderForm( 'core_color', @$options2['bg_color_first_entry'], $config, array( 'label'=>'Background Color First Entry', 'defaultvalue'=>'#ede7b7', 'selectlabel'=>'', 'options'=>'', 'storage_field'=>'json[options2][bg_color_first_entry]' ) );