Using Vim key bindings in Onenote
Solution 1:
You should be able to do with AutoIt (or possibly AutoHotkey) scripting, but I could not find anything that has already been written.
Solution 2:
Vim-Keybindings-For-Onenote brings the power of VI to onenote via an AutoHotkey plugin.
The plugin has many of the common key bindings, including the folding commands to help manage OneNote lists.
Some advanced key bindings (e.g. 5dfa) are not implemented, but if there are keybindings you'd like added, the author (that's me), will help as he can.