It is not really easy to create something like that inside CC since it mostly intended to "sculpt" a human body.
Now, if you want digitigrade legs on human torso, you can morph such a character outside of CC and import as a morph slider with option to Adjust bones.
This is a basic workflow with Blender in mind: It is for CC3.2, but applicable to CC4 as well.
The only difference is that you may want to select CC3+ Neutral Base to create a morph.
I did not mean to be very artistic here. But I sculpt those rather quickly in Blender and imported as a slider into CC based on above workflow..
Once created this morph could be applied to any character for legs transformation.