A big bench vise is almost mandatory. I clamp the entire case in the vise, vertically. I use one of the large webs as a clamping point.
The first time you separate the cases, you will probably need to use some long bolts and the separation ears that are cast into the cases. These will allow you to forcibly yet slowly go back & forth turning the nuts until you overcome the super sticky bead of goo that glues them together. After that...the upper half can be lifted off. The shifter fork shaft has a small delicate pin on the end of it that can easily be broken off. The chain has a top and bottom...make sure you get that right. Also the sun/planet gears have index marks that must be correctly aligned.
Overall...its not that hard...just get a clean, well-lit, bench and lay out all the parts in the same orientation you remove them. Take photos to help you get it back together correctly. Also...download the manual from Schwarttzy.