Programmically add custom date filter to views

When programmically use views, two function is very important:

//get results only, i.e. return array of values
views_get_view_result($name,. $display_id);

//return themed html from views
views_embed_view($name,. $display_id);

These two functions provide PHP developers more control over views.
By looking at the source code of them, you get the idea to $view object

So as views/date module do not yet provide a context filter to "larger than created date" (need review)
so I use some custom code to add custom filter to views:

// API: add_item($display_id, $type, $table, $field, $options = array(), $id = NULL)
// add custom filter programmically
$view->add_item($display_id, 'filter', 'node', 'created',
'value' => array('type' => 'date', 'value' => date('c', strtotime($strtotime_string))), 'operator' => '>='));