The config.js file sets all of the map and query parameters. So as long as you are setting the proper map to query and the fields in that map to use for the avery labels then all should work.
This is the part of the config.js file that sets the map that will be queried.
// Map Services for operational layers
TaxParcelPublishingLayer: "yourRESTlayerNamegoeshere",
When it queries the above rest layer, it will snag whatever fields you have in this part of the config.js to fill the avery label. In my case, I use different fields also and everything works as it should:
//Fields for Avery labels
AveryFieldsCollection: ["OWNER_NAME", "ADDRESS_1", "ADDRESS_2,ADDRESS_3", "CITY_NAME,ST,ZIPCODE"],
Hope this helps,
Luci