Update on my findings:
Well, I can claim partial success with Adobe Acrobat Pro 9.
I made the form and it worked on a Mac using Acrobat Reader but with the following exception: The tab movement through fields wouldn't work on the radio buttons or the drop down boxes. It would only tab through the text boxes. For the drop down and radio buttons, I needed to access them with the mouse.
Otherwise, you could edit the form, save it, then open it up and edit it again, all using the Acrobat Reader.
It worked pretty well.
So there you go.
@#$% Mac... grrr..