How do I: make a Tooltip for text in a Word document

[neoxml]

I want to make a macro that returns any word string (the key) the
cursor hovers over in a Word document and then checks it against all
keys in a HashTable. Then it would return back to the document the
associated value, if there is a match, and display the returned value
in a tooltip over the word it received the string from. Has anyone
done anything like this? Additionally, I do not want anything left in
the document so the use of comments will not work.

Any help on solving this problem will be greatly appreciated.

Michael M