I have not had much luck in hunting down what is wrong with my code or the Xerces-c SAX2 parser – but I do think I have successfully updated by hex editor, Hexxed, to handle 64 bit (ie >4GB) files.
Indeed it performs rather better than vi for some editing tasks (Hexxed has a vi like interface).
So, if a hex editor, capable of handling little and big endian code and able to display output in Unicode is what you are after, and if you are vi-conditioned, then maybe Hexxed is your thing.
While a runnable jar for those of you who have Java but are not yet Groovy can be downloaded at: http://184.108.40.206/hexxed.jar
And there is more about it here: https://cartesianproduct.wordpress.com/2012/06/03/hexxed-usage-options/
Just remember it is code for playing with – don’t bet the farm on it. But, that said, I have no reason to think it does not work.