Welcome to the forums.
One of the main strengths of FlashHelp is that it works
cross-browser and cross-platform. Also, if you have Adobe Flash and
know a little about editing objects and frames, you can edit the
Flash skin files to make them look pretty much any way you like
(one of the reasons I use FlashHelp). In particular, the Slate skin
already has a tabbed look, so that one may give you a head start.
The default toolbar buttons/tabs are Contents, Index, Search,
Glossary, and Print (in whatever order you specify when you
generate the FlashHelp output).
Rick Stone's site has loads of
information about manipulating buttons in the toolbar, so you may
find info on making toolbar buttons/tabs do what you want there. In
Rick's table of contents, click Grimoires > Skinny on Skins and
download one of the files.
Hope this helps,
Ben