Rated 1 out of 5 stars

Since this hasn't been updated since Firefox 3.1 I politely point you to my alternative extension: Geo Relocate

http://www.netzgewitter.com/georelocate/
or
https://addons.mozilla.org/firefox/downloads/latest/8420/addon-8420-latest.xpi?src=addondetail

Rated 1 out of 5 stars

The links are all broken, I have found a blog post from the author that might help
http://dougt.org/wordpress/2010/06/geolocation-setting-your-position-manually/

Rated 2 out of 5 stars

tries to use Firebug's icon; options dialog does not remember previous location; fuzzy geolocation always returns 0, 0

This review is for a previous version of the add-on (0.4.1).