WeatherKitten (WeatherCat iOS client) V1.0.0 B97 is now available in beta! See https://athena.trixology.com/index.php?topic=3714.0 for more details.
For a Vantage/Vue/Envoy, open the station hardware options from the Tools menu, then hit the 'Set Channel Names' button at the bottom to edit the names. You'll have to reboot WeatherCat after making the changes you want.