I can't however figure out how to use and URL with ReadStream("littleendian::" + FileName) since the littleendian string expects a string to be added to another string and if I convert the URL to a string then what's the point?
Not quite sure what you mean here... if you leave it the way it is, ie. ReadStream("littleendian::" + FileName), it should work fine, whether the file is external or IncBin'd into the executable. Any file that's passed to it will be read in little endian byte order.