GeoNames API for Drupal - the whole world in one function

I posted this on the module issue queue on the Drupal site, as well.

In my application, I am using the location module (non-CCK). I require nodes to have country, state / province and city. I harvest country and state via dropdown selects (and thus have the alphanumeric code provided by location module). City is then entered via a location-module text field.

I am very impressed with the geonames service and appreciate the work done here but I find the documentation a little thin - - and BTW, I would be happy to contribute code examples and other How-To's once I get my arms around this.

So - - Given country and state / province, I would like to do the following:

1) obtain a list of named cities for this country and state / province pair.
Having obtained this, I would then make certain the city is correctly entered.

2) once I have a valid a city, if the user enters zip / postal (this field is optional), I would then like to obtain a list of zip / postal codes for that city and make certain that the city - zip pair is valid.

3) alternatively, if the user enters zip / postal first, and then city, I would like to submit country and zip / postal and then check the city.

timely help would be greatly appreciated and I reiterate my offer to help - - and this includes creation of graphics if needed.

I have tried many variations using the geonames_query function with no luck.

thanks so much

S