See the following two links on how to create a concordance, and how to use that to make an index of all words.

One
Two

That looks like a real project - once you've finished it, could I ask you to post what you did and how it worked - I'd be interested to see if I could create some VBA code to follow through the steps in case it needed doing again!

Oh - and here's a link to a bit of code to help with the Excel stage.