I'm fairly sure I've seen it on many other skins, so I just stuck it in there. I'm sure it is possible to do in RR now. I thought it was built-in, but even if it is not I'm sure there is an add-on app that makes it into a label or something. Worst case, you could get an app that just displays it with a transparent background in that location.
its built into RR,
any of the commands and labels you see in the weather screens can be used anywhere.
Thats the best thing about RR skinning, your not limited to only having certain functions on certain screens.
I think most people dont use it on the main screen cuz you have to have internet access for it to display the values.
I think you can get the temp from your GPS, not sure if that works in RR (i maybe be way off base though about gps temp)