Here's our solution, where we're using plus and minus icons
instead of open and closed books (bookicon, collapse_tbar.gif, and
index.htm are my names, so use your own):
In the Skin Editor, Toolbar tab, Add an Item
In Text tab -
Item Name: bookicon
Image Options: Custom: collapse_tbar.gif (both Selected and
Unselected)
In Action tab -
Action: JavaScript: OnClick: parent.location='index.htm'
(the project Start Page)
In the WebHelp Navigation (Window 2) Toolbar Buttons panel
select the 'bookicon' option and move it all the way to the top,
which will place it before the Contents button.
You'll probably have to experiment with sizing and spacing
issues for your icon image (such as adding 20-or-so blank pixels to
the right of it, etc.).
Good luck,
Leon