How to create single installer?

I'm finding this to be a real challenge. I have successfully created a Word and Excel add in. Using VS2008, by default two separate installers are created. I would really like to wrap this up in a single installer, but I'm not having any luck at all.

I tried simply (and I say simply lightly, as it is very tedious) to duplicate all the registry info, custom actions, etc from the Excel installers into the Word installer and added the appropriate outputs to the Word installer that were in the Excel installer. After running this single installer, it appears that everything has installed correctly (files, registry settings, etc) for both Excel and Word, only the Word add in continues to work.

I realize I must be missing something in the installer since surely the installer is not tied to the specific add in that it was created with, is it? But I'm have gone over everything with a fine tooth comb and I don't appear to be missing anything.

Any help would be appreciated.