$(document).ready(function(){
var path = "<?php echo $this->Html->url('/app/webroot/uploadify/') ?>";
$('#file_upload').uploadify({
'buttonText' : 'SELECT FILES',
'formData' : {
'<?php echo session_name();?>' : '<?php echo session_id();?>',
'webroot' : '<?php echo WWW_ROOT; ?>',
'ds' : '<?php echo DS; ?>'}
,
'swf' : path + 'uploadify.swf',
'uploader' : path + 'uploadify.php',
'removeCompleted' : false
}

});
});

uploadify.php

$targetFolder = 'files'; // Relative to the webroot

$www_root = $_POST['webroot'];
$ds = $_POST['ds'];

$tempFile = $_FILES['Filedata']['tmp_name'];
$targetPath = $www_root . $targetFolder;

$needle = array( ' ', ':', '/', '\\', '#', '*', '\'', '"', '´', '`', '!', '?', '@', '$', '%', '&', '=' );
$file = str_replace(' ', '_', $_FILES['Filedata']['name'] );
$targetFile = $targetPath . '/' . $file;
$n = 1;

$file_1 = $file;
while(file_exists($targetFile))
{
$file_1 = $n . '_' . $file;
$targetFile = $targetPath . '/' . $file_1;
$n++;
}

move_uploaded_file($tempFile,$targetFile);