I am asumming you are trying to figure out where the tile is on the tileset.. like how many tiles to the left and down to find the tile you see in the level.. It would take be a bit to explain but if you understand php maybe you can cut out what you need from this:
http://pastebin.com/f74418c73
But to try and explain it simply.
PHP Code:
$base64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
$temp = $test[$k][$i]; // your tile number
$tile = dechex(strpos($base64,$temp[0])*64+strpos($base64,$temp[1])); // the hex value for tile
$tilex = hexdec(substr($tile, 0, -1)) % 32;
$tiley = floor(hexdec(substr($tile, 0, -1))/32)*16 + hexdec(substr($tile, -1));
But I think I may have had my x and y backwards.. either way it should give you the positions.. this is kinda old.. wish I could find the post that explained it on the the forums..