Hi tobias,
TOCs in Pages are generated automatically using the headings and sub headings inserted in the documents.
If you can set the main headings Style to include a Roman numeral, and the styles for the subheadings to use Arabic numerals, Pages may be able to collect the style with each heading, and apply it to the TOC entry for that level.
If that's not successful, you may have to build the TOC manually, with the numbers added as text.
Do you know if this requirement is part of a widely accepted and applied requirement for the type of document your wife has had assigned, or is it the requirement of only a minority of persons, departments or organizations in this field?
If it is widespread, I'd suggest clicking on the Provide Pages Feedback menu item in the Pages menu and requesting that this ability be added to Pages' feature set.
If it is not widespread, you could still, and probably should still make the request. Its lack is an issue for anyone using Pages to complete an assignment with similar specifications, and adding the capability would make those lives easier (and less stressful).
Regards,
Barry