Add another tab right aligned with no leader (None) at the edge of.The first right aligned with '.' leaders at just before the edge of the page (e.g 14.5cm on a portrait A4 page). In the new dialog click the Format drop down button and select Tabs.Click the Modify button down the bottom right and make sure TOC 1 is selected in the styles list.Right click on the TOC and choose Edit Field.Press ALT+F9 to display field results again. Scroll up to your table of contents and press ALT+F9 to show the field code.
It involves adding the prefix to each heading in the document as hidden text and formatting the TOC styles in a special way.
There is perhaps one way to achieve this, but it is a work around and is a bit complex to setup (however easy to use).
