I am importing XML into InDesign, and I get this message:
The external entity \'blahblah.dtd\' cannot be found. Continue to import anyw
I think zanegray gave you the main concept although I think you overcomplicate stuff. Why not just getting xml file content, remove teh dtd declaration with a regexp and then output a new XML File that will be used for input ?
//Open and retrieve original xml file content
var originalXMLFile = File (Folder.desktop+"/foo.xml" );
originalXMLFile.open('r');
var content = originalXMLFile.read();
//Looks for a DOCTYPE declaration and remove it
content = content.replace ( /\n/g , "" );
originalXMLFile.close();
//Creates a new file without any DTD declaration
var outputFile = new File ( Folder.desktop+"/bar.xml" );
outputFile.open('w');
outputFile.write(content);
outputFile.close();
You can then use this filtered xml for your import.