I am looking to do something similar to http://eslifeline.wordpress.com/2008/09/05/inserting-image-in-a-xdp/
This example pulls in a encoded image from a text file along with some other xml data.
I am creating a flex application to create an image and write to either a database, the file system or directly to the LC repository.
Then I have a process similar to the one in the link that will render out a pdf.
Retrieving data ...