All I need to do is pass along the value of a custom form element to upload.php. lets say I have called it extraData. This should be read as normal POST data each time a batch of uploads start... I know how to deal with everything else I need to do, just need to get my value to the upload form.

Here is the code below, this is taken from a modx plugin so it may look a little funny.

Thanks!

<script type="text/javascript">
<!--
$(document).ready(function(){
$("#uploadify").uploadify({
'uploader': '[+base_path+]js/uploadify/uploadify.swf',
'script': '[+base_path+]upload.php',
'checkScript': '[+base_path+]check.php',
'scriptData': {[+params+]},
'folder': '[+base_url+]assets/galleries/[+content_id+]',
'multi': true,
'fileDesc': 'Image Files',
'fileExt': '*.jpg;*.png;*.gif',
'simUploadLimit': 2,
'sizeLimit': 2097152,
'buttonText': 'Select Files',
'cancelImg': '[+base_path+]js/uploadify/cancel.png',
'onComplete': function(event, queueID, fileObj, response, data) {
var uploadList = $('#uploadList');
uploadList.append("<li><div class=\"thbButtons\"><a href=\"" + unescape('[+self+]') + "&action=edit&content_id=[+content_id+]&edit=" + escape(fileObj.name) + "\" class=\"edit\">Edit</a><a href=\"" + unescape('[+self+]') + "&delete=" + escape(fileObj.name) + "\" class=\"delete\">Delete</a></div><img src=\"" + unescape('[+thumbs+]') + "&filename=" + escape(fileObj.name) + "\" alt=\"" + fileObj.name + "\" class=\"thb\" /><input type=\"hidden\" name=\"sort[]\" value=\"" + escape(fileObj.name) + "\" /></li>");
},
'onAllComplete': function(){
$(".thbButtons").hide();
}
});
$('#uploadFiles').click(function(){
$('#uploadify').uploadifyUpload();
return false;
});
$('#clearQueue').click(function(){
$('#uploadify').uploadifyClearQueue();
return false;
});
if($('#uploadList').length > 0){
$(".thbButtons").hide();
$("#uploadList li").live("mouseover", function(){
$(this).find(".thbButtons").show();
});
$("#uploadList li").live("mouseout", function(){
$(this).find(".thbButtons").hide();
});
$(".thbButtons .delete").live("click", function(event){
if(confirm('Are you sure you want to delete this image?')){
$.get($(this).attr('href'));
$(this).parent().parent('li').remove();
}
return false;
});
$(".edit").live("click", function(event){
var link = $(this).attr("href");
var overlay = $(this).overlay({
api: 'true',
target: '#overlay',
oneInstance: true,
onBeforeLoad: function(){
$("#overlay .contentWrap").load(link, function(){
var keyword_tags = new TagCompleter("keywords", "keyword_tagList", ",");
});
},
onClose: function(){
if($('.newimage').length > 0){
window.location.reload();
}
},
onLoad: function(){
$("#cmdsave").click(function(){
overlay.close();
});
$.urlParam = function(name){
var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(link);
return results[1] || 0;
}
$("#newimage").uploadify({
'uploader': '[+base_path+]js/uploadify/uploadify.swf',
'script': '[+base_path+]replace.php',
'checkScript': '[+base_path+]check.php',
'scriptData': {[+params+], 'edit': $.urlParam('edit')},
'folder': '[+base_url+]assets/galleries/[+content_id+]',
'multi': false,
'fileDesc': 'Image Files',
'fileExt': '*.jpg;*.png;*.gif',
'simUploadLimit': 2,
'sizeLimit': 2097152,
'cancelImg': '[+base_path+]js/uploadify/cancel.png',
'onComplete': function(event, queueID, fileObj, response, data) {
$('.thumbPreview').empty().append('<img class="newimage" src="' + unescape('[+thumbs+]') + '&filename=' + escape(fileObj.name) + '" alt="' + fileObj.name + '" />');

}
});
$('#newimageupload').click(function(){
$('#newimage').uploadifyUpload();
return false;
});
}
});
overlay.load();
return false;
});

$("#uploadList").sortable();
}
});
-->
</script>