Well because i dont know how to take out the front so just download the theme down and install it. After than u can install a different theme over it and the fonts will be there still.
Or u can try to delete the framework and app inside the folder and install it (dunno if it will work because i never try it)
And if anyone else got any kind of fonts that can install in G1 please post it here for sharing.
Here below is some pic about my fonts: