I can open and edit in TextWrangler on the Mac. TextWrangler from BareBones Software is free.
My preference is Oxygen Author but that's a paid application which allows editing without cracking open the EPUB.
I was able to open the toc.ncx file in TextWrangler, but the code made no sense to me. I made a few changes that seemed obvious, but there was no change whatsoever when I closed the ePub and imported it back into iBooks.
Is there an online tutorial for editing toc.ncx files?
I can't understand why this is such a difficult thing to do. Very frustrating.
"There doesn't seem to be a way to edit the toc.ncx file in DreamWeaver"
Actually there is. You just need to add ncx to Edit/Preferences/Open in code view.