It's all in the wiki.
You just need to assign shortcut to action that toggles contextual toolbar. If you edited preset 1 of contextual toolbars, simply search the actions list for:
Code:
sws br contextual toolbar preset 1
and then keybind the action to whatever keys you want.
Btw, I see that wiki is lacking information about what different actions do
(exclusive toggle vs open/close) so I updated it.
http://wiki.cockos.com/wiki/index.ph..._load_toolbars