Ive looked at some tutorials on the web, but there doesn't seem a simple solution.
However, I have been experimenting, and this method seems to work fine.
First off create your Watir::IE object
ie = Watir::IE.new
Then navigate to the page you are testing
ie.goto("mypage.myserver.com")
Grab the descriptor of the element you wish to send a keyboard command to (for example, a text field)
element = ie.textField(:id, "myText")
Now, I found that keyboard events only work if the Watir::IE window is on top and has focus, so for example if we wish to send a "Pageup" keyboard command to the element "myText" we would do so by
ie.bring_to_front
element.focus
element.container.focus
element.container.send_keys("{PGUP}")
This method does require Autoit(http://www.autoitscript.com/autoit3/) to be installed, and a full list of keyboard events can be found here: http://www.autoitscript.com/autoit3/docs/appendix/SendKeys.htm