If there had been such a tutorial, it might very well now need to be rewritten ;-)

As I understand it the "intensity" of the envsphere can be adjusted via the "Value" property of the HSV node, in BB's default shader for it.

I've customised my copy of the envsphere, so that that Value property, of the HSV node, in the envsphere shader, is animatable (i.e. by clicking the little key next to the property in the mat room node)... making a dial appear in the Prop dials, which I've just named "Intensity".

The thing is most of this stuff is additional... add-on technique / knowledge / utility... to the actual Poser program, at present... the envsphere, EZSkin, etc...

But also, everyone is aiming for slightly, or completely, different results. So each person's workflow will likely differ slightly... no matter what.