Customizing CiviReport containg custom datetime fileds that have time part

When customizing reports that include custom data it is easy to get searchable custom data field by including 'protected $_customGroupExtends = array( 'Participant', ... );'
However for datetime fields that have time part the report does not show time, but only date.

Use case - we use event registration and custom data to collect arrival date and time so that we can organize airport pickup for event participants. Online form works fine, but it is not easy to get this data on the report.

(see forum http://forum.civicrm.org/index.php/topic,16103.msg68798.html#msg68798)