Hello,
There is no way to create a Table of Contents like you do in Word. One way you can do is by puttng headers to your sections and then have Show/Hide buttons at the end of the header. By default you can hide the sections and show only headers which look like a Table of contents.
When ever Show button is clicked the section will be shown below.
I hope this will help you.
Kalyan G Reddy
Infopath MVP 2007 and 2008