Manual is your friend grin Simply use c_scan. Enjoy!

Code:
function scan_your_entity(){
	c_scan(player.x, player.pan, vector(100, 600, 300), ignore_me);
}

on_ctrl = scan_your_entity;


function skener() 
{
  if (event_type == EVENT_SCAN) 
  {
    you_see_entity = 1;
  }
}

action your_entity{
	static_entity=me;
	my.ENABLE_SCAN = ON; 
	my.event = skener;
}