Zip code proximity search

I need to create a zipcode proximity search for a site I am building. It looked like your plugin was going to be the answer, but I am running into a problem. I want to create a profile search form for BuddyPress that allows people to search within x miles of any zipcode they type in. When I try to create a field to do this In Geo My WP, it looks like the only options are to search within a proximity of the user’s location or to do a zipcode search that only shows the exact zip code typed in. Because of the nature of the site, I need to be able to do a proximity search of any zipcode entered in the search form, not just proximity to the user’s location. Please let me know if there is a way to do this.