Do you mean, you want to know how to assign midi controls to various parameters within a vsti and then use the automation to record the controller movements? Some of them are automatically assigned but some of them aren't. There is a way that you can customise what your midi dials and sliders control but i've only done it once and it was really difficult. I have just seen a video tutorial on googlevideo about this though. Go to googlevideo and type in cubase tutorial and then try the vids 69-71. I think this is waht you're after. Let me know if this is any good.