As far as I know, there is no simple direct way for upgrading from 6.x to 7.6.x
Refer to below white paper, it talks about upgrade from 7.0 to 7.6.04 -
This will give you an idea about moving customizations from old versions to 7.6.4
Hope this helps.
i am unable to access the link you have given..Can you please forward that pdf to my mail id.