Required software

Active Python 32bit 2.4 or newer. (Plain python with win32 extensions probably works but I only test with Active Python distributions) Make sure you get the 32 bit version. It will not work with the x64 version.
Outlook (of course). I've seen this work with:
- Outlook 2007
- Outlook 2003

Installation

Download the smartquoteaddin.py file to somewhere on you computer.
Close Outlook if it's running.
Bring up a command prompt.
cd to the folder containing smartquoteaddin.py
Run python smartquoteaddin.py (you should see a message about successful registration)
Start outlook. Look for 'Ken's reply' buttons created on your toolbars. You can right click to rename these to whatever you like.
Warning: Some users may experience outlook crashes on startup when using this plugin. Outlook will blame this plugin, and will ask whether to disable it. To prevent this crash, one needs to disable outlook.exe from being run with Data Execution Prevention. I've personally seen it running Outlook 2007 on a Windows Server 2008 x64 machine. The CPU must also support the feature, so whether you see this bug will depend on what CPU you are running.

Uninstall

To uninstall, run the smartquoteaddin.py script with the --unregister option. I.e:

python smartquoteaddin.py --ungregister

Development Notes

The whole thing works because of the awesome work that was put into python's COM bindings on win32 platforms. The code is essentially a modified example of COM usage (and specifically, outlook add-in usage).

To hack on the code, it's good to have the outlook com api notes handy. If you google for 'MailItem' you're pretty much bound to find it.

Look in the .py file for debugging help. It requires you have the pythonwin IDE around, but if you installed Active Python, then you should have it already.

On x64 machines, it looks like you need to still install ActivePython's x86 version. It appears the win32 stuff hasn't been ported to x64 quite yet.