UTF-8 vs UTF-16 File Polling

I've created a file polling WSDL that picks up an XML file.  This works fine, except that the process errors out with "content not allowed in prologue" if the input file is anything but UTF-8.  The XSD used to create the WSDL is UTF-16, and is labeled as such in its header.

If I change the header of the input file to say UTF-16, even though the file is UTF-8, and the XSD header says UTF-16, it still works.  But if I change the input file to "Unicode", and label it UTF-16 in it's header, the file pick-up fails.

Eventually I need a UTF-16 file to be read.  Is there some trick to picking up a UTF-16 XML file using a file polling WSDL?

On a side note, the XSD that defines this file hangs the GUI BPEL editor completely, every time an attempt is made to access it in anyway, such as an Assign.  Editing the BPEL XML by hand in the source view worked perfectly however.  The XSD and the BPEL both validate and compile fine.

Thanks