Honestly, doing this is not as daunting as you think. Work slowly and TAKE NOTES, NO MATTER HOW MUCH YOU THINK YOUR MEMORY WILL SUFFICE. There are plenty of cheap lenses around. You need a set of miniature screwdrivers (I got several sets at the Dollar Store years ago). For a 'spanner wrench' I use a very pointy pair of scissors (used for cloth)! I improvise always. Through the years I have kept tiny screws of all sizes that I keep in a small sealed container. Slowly, and frustratingly, you will learn some absolutes about lenses and also some things that can be different. You will break things. You will lose ball bearings that are used for the aperture click stops. You will lose the tiny screws that support those ball bearings.Some things you will not break. Always (and I need to learn to follow my own advice here) put a clean towel underneath the lens so that if something tiny drops you will not be searching on your floor that that item.

Learn and understand that slow is better and still, no matter what, you will fail at times. And there really will be times that you spend many hours only to finally break the damn thing; but you have learned ... and no one can take that away from you. - David Lyga