mmmm, complicated process? It's fairly simple!
Please, read the documentation about Upgrade, and try first in local, if you prefer, always with a copy of your database as Backup, just in case any minor problem arose.
I offer to help you, if you also offer to improve the documentation (http://doc.tikiwiki.org/Documentation) where needed (and "if" needed ), with the information some of us will give you, wherever you get lost from the current documentation pages.
You might get some warnings of duplicated indexes, xxx already exists, etc. but they are just to tell you that tiki checked if that was created, and attempted to re-generate that table, index, or whatever just in case.
I've invested already some hours for you to update the documentation pages, but screenshots are not in English.... (that's something easy you can help with: take screenshots of your whole process in English, and update the docs. when you are sure that you understood the process, etc.
What do you think about it?