Disappointed at being unable to assign a key to most emotes, I've made an AutoHotkey script to allow you to use the Numpad for Emotes. It uses Numpad0 as a "shift" key, allowing up to 30 quick-access emotes.
The script also provides Ctrl-Backspace as "clear chat," and I personally have "E" mapped in-game to "/helpme" for even quicker access (AHK can't tell when you're in a text control, so if you map it in AHK you can never type E).
You can customize them however you want; the syntax should be pretty intuitive even for people who haven't seen AHK before. You can substitute any button and any command, not just the numpad and emotes. Note that if you use the keyboard to move but NOT WASD, you'll need to replace all the w's, a's, s's, and d's in the c() function. Also note that the script relies on you not having changed the "Start Chat Command" shortcut from '/'.
I was also wondering if I'd be allowed to stick this on the Wiki somewhere, perhaps at the bottom of Controls/Custom Controls?
"6. Restrictions
You agree not to do any of the following prohibited actions: (...)
13. modify any files or use any game hacking/altering/cheating software or tools, including scripting or macroing software, or attempt to disassemble the game client and/or decipher the data transmissions between Spiral Knights' client and server. These activities will result in immediate termination of the Player's Account and may subject you to civil and/or criminal liability. "