Yes you are right it will not work because your segment got a p(p2)
To do this you must have to modify the core but i will say dont modify the core just extend the pagination class and modify the code with following:
Add a new class variable
var $use_rsegment = FALSE;
Then modify the create_links()
around line 157
//add
$_uri_segment = 'segment';
if($this->use_rsegment){
$_uri_segment = 'rsegment';
}
//modify
if ($CI->uri->$_uri_segment($this->uri_segment) != $base_page)
{
$this->cur_page = $CI->uri->$_uri_segment($this->uri_segment);
// Prep the current page - no funny business!
$this->cur_page = (int) $this->cur_page;
}
The uri rsegment is the new routed segment, now set the pagination config like this
$config['use_rsegment'] = TRUE;
$this->pagination->initialize($config);
So you can use both option when ever you need. When you have route set rsegment true