Hi Fred,
Sorry for the delayed response.
Please refer to the forum thread below that has a sample demonstrating the drag and drop operation with the custom data.
http://www.syncfusion.com/Support/Forums/message.aspx?MessageID=17221
http://www.syncfusion.com/Support/Forums/message.aspx?MessageID=18162
Let us know if you need any further information.
Thanks,
Rajagopal