UPDATE: The timeout feature is even more broken, if possible; these workarounds will no longer work. Using Firefox 10.
After several versions, Mozilla still has not fixed the accessibility.typeaheadfind.enabletimeout setting related to linksonly. If it worked, setting it to false would keep the Find bar at the bottom of your screen until you pressed Escape. But setting it to false does nothing, which is potentially unfortunate for people who type very slowly or use switch scanning keyboards to access links. The timeout persists no matter what. You will have to select the accessibility.typeaheadfind.timeout entry, right click it or press Shift F10, select Modify and enter a very high number.