If you dont see the cs files maibe the problem is that you are working with the compiled version, and not with the full code. You can read this articule about getting the last source code http://www.mojoportal.com/getting-the-code-with-tortoisehg.aspx.
Read in the dev documentation about how to create your own user controls, please follow this link
http://www.mojoportal.com/addingfeatures.aspx