geouser adding a class to <dt> tags

My issue is pretty simple to explain but not so simple to fix (at least not for me).

The following code is generated within the profile page

I would like to add a custom class to <dt>City</dt> without hacking the module.
I assume the answer will be most likely using template.php.

Unfortunately, I don't have a full undestanding how template.php works and therefore I would like to ask for help with this one.

And just an additional note... using

won't the job since I need <dt>city</dt> to float: left but I need <dt>Geographic Map</dt> without float...

Any ideas or suggestions are greatly appreciated.

Thank you!