I haven't touched C2 for a while now but I assume that you can build your application for a specific screen size then check the ratio of the current device screen size, then apply this ratio with the SetLayerScale:
Let's say your application runs in 1000x500 by default, then the device running your game is 1200x600, then you get a 1.2 ratio. You can probably use the SetLayerScale with the 1.2 ratio to resize your game..
I guess it would look like something like this:
It's probably not working exactly like that in C2 but that's the idea.