When I\'m debugging, I often have to deal with methods that does not use an intermediate variable to store the return value :
private int myMethod_1()
What you need is Mocking. Checkout mocking frameworks like Rhinomock, Moq or Typemock.
For the kind of scenario you are describing, I am going to assume that you may not have clean contract - driven development and may need to return in fake behaviour/state. In this case, Typemock may be the best option for you although it is commercial