If you are using City Navigator, all the fire stations are probably in the map data already, under "Community". Just center the map on your grid waypoint by selecting it in the list, right clicking and "show on map". Then use the Find toolbar or the binoculars to search POI's for "Fire Departments". They will be listed by distance from center of map, which you have just centered on your waypoint. Use the route tool to autoroute from your waypoint to whichever station you want and either save it as is or fix the route to your liking.
If you don't have CNNA, you will have to create all the waypoints manually, and use the ruler tool to find the distances from the grid waypoint, then create your routes manually. BC will NOT search for waypoints since they are already listed in the list.
If your eventual use will be to load these routes into a GPSr, you can instead create a custom POI list of your stations and use POILoader to upload it to the GPS.
http://freegeographytools.com/2008/creating-a-garmin-poi-datafile
Then when you look under Custom POI's or Extras, or whatever your Garmin GPS calls it, you will see all Stations listed in order of distance, click on one, and if your map is routable, bingo, you're back on the map page with the route to that station displayed.
I need the route distance instead of as the crow flys.
As I understand it you want, from some arbitrary position, to have the unit (re)calculate routes to all fire stations and then display those in order of distance? I don't think this is possible. As the crow flies is as close as you get.
I'm pretty sure MapSource and BaseCamp can't either.
Dead simple in BaseCamp aslo--create the routes as described, then switch the data and map views so the data view is in the main panel....Columns will appear showing various route properties including route distance. Click on the route distance column heading and the routes will then sort in order of routed distance....