Geotag Comments

I have a wordpress blog located at http://www.gstuart.adalpe.co.uk. We are interested in having all coments posted by users geotagged. This is so that when we have debates, etc. We can see where our users are from, (firstly, to help defeat SPAM. Secondly so that when we send out press releases about the debates we can decide weather to send local or national ones out.

It is very valuable information. I have looked through the plugins section extensively and discovered many plugins for geotagging posts, but not comments. I would preferably like to have it automatic based on the IP of the poster, but a manual “tag yourself” would be acceptable

Any help is appreciated.

Thanks

Adam.