<?php

function assign_to_array(&$array, $keys, $value)
{
  $a = &$array;
  $total_keys = count($keys) - 1;
  foreach($keys as $key => $val)
  {
    if (!is_array($a[$val]))
    {
      $a[$val] = array();
    }
    $a = &$a[$val];
    if ($total_keys == $key)
    {
      $a = $val;
    }
  }
}

$array = array(1, 2, 3);
$keys = array('a', 'b', 'c', 1, 2, 3);
assign_to_array($array, $keys, 'someValue');
var_dump($array);
?>