In 2007, open the Styles & Formatting panel (Ctrl-Alt-Shift-S), click
Options at the lower right. In the Show What? dropdown, click All
Styles. Go back to the S & F panel, scroll to the ToC2 style name
(whatever it happens to be), and right-click on it, and choose Modify.
Then Format > Tabs, select the entry for the one at the right edge,
and click the dot-leader (should be the second choice of leader, after
"None"). Then OK your way out.
(Oh, you'll probably want to turn off Show All Styles!)