This feature isn't supported by Pages '09. If you want to do this you'll have to switch word processing programs or manually create your Master Table of Contents.
Each table of contents (TOC) you create using a Word Processing
template lists only the content that follows it, up until the next
table of contents. If you want a master table of contents for the
entire document, it must be the only table of contents, and it must be
at the beginning of the document.
Source: Apple's Pages '09 User Guide (page 64). The same information can be found using Pages > Help and searching for Creating and Updating a Table of Contents