The first step is to save the coordinates that appear as a text file. These can then be used with GSAK (see http://gsak.net) or the workhorse underlying GSAK, GPSBabel, to filter caches. If you don't use GSAK or GPSBabel then these files will be of limited use.

Here are the down and dirty basic steps you'll need to follow to use the files with GSAK:

1. Populate your GSAK database with caches using Pocket Queries (or individual cache downloads). You will need to cover the area of interest; i.e. if you are looking for caches along I-90, for example, you will need to generate Pocket Queries that cover its entire length.
2. In GSAK and with your intended database active, select "Search/Filter..."
3. Select the last available tab on the dialog labeled "Arc/Poly"
4. If you downloaded a route file, select the "Arc/Line" radio button, select the distance from the route in which you want to filter (to find caches within a half-mile of the route, for example, you would want to enter "0.5"), then click the "Load from file" button under the "Arc/Polygon points" field. Navigate to where you saved the downloaded text file and select it for load.
5. If you downloaded a polygon file, select the "Polygon" radio button and then click the "Load from file" button under the "Arc/Polygon points" field. Navigate to where you saved the downloaded text file and select it for load.
6. Select any other options you want on the other tabs of the dialog
7. Click "Go"

Now, the caches in the database will be filtered based on the criteria you set. If you wanted all caches within 0.1 mile of the freeway, you will now see a list that fit those criteria. If you wanted all caches contained within San Juan County, you will now see that list. The caches can then be exported as a file (GPX or other format) and even uploaded directly to your GPSr.