Connecting a HDE keyboard to a Kindle Fire
The USB port is not powered on the Kindle Fire, and thus cannot host USB devices.  So, a wired external keyboard connected directly to your kindle is pretty much out of the question.

What if you were to power the keyboard some other way?

Well... that seemed to be the question this one gentleman asked himself.  He decided that connecting a powered USB 2.0 hub to the kindle, and then connecting the devices to the hub would be the way to go.  He found he needed a USB OTG cable to start the process.  He hooked up the hub, plugged in the mouse, and saw a mouse cursor.  He connected a keyboard, and could type.

So.. that's my advice.  Get yourself a powered USB hub.  Of course, unless you then got creative with supplying power to the hub via a battery pack, you are limited to using the keyboard to wherever you can plug the hub in... but that's still a step in the right direction.