Do you have an Apple Bluetooth keyboard that refuses to link with your iMac after installing rEFIt? Here’s my short story for those with similar problems looking for a solution.
You might just be searching for the solution, so here it is.
Unplug all input devices from your iMac and reboot. Once you get to the login screen, Mac will start complaining that there are no input devices and will open the much needed dialog box that will allow you to relink the wireless keyboard with the iMac. After the dialog box appears you will need to reattach your mouse. From there you can navigate the menus with just the mouse to link the keyboard once again.
Using this trick I have been able to complete my triple boot setup [Mac, Windows, Ubuntu] without having to touch a wired device
There appears to be some special code in the stock Apple firmware that facilitates linking wireless bluetooth devices at an early stage. However, rEFIt does not have this same functionality and because it takes over for Apple’s version, you’re plum out of luck.
The most convenient solution is to grab a wired keyboard, something which I have not possessed in over a year. With a wired keyboard you can get logged back in and reconfigure the keyboard on the software side through System Preferences. But what if you’re like me and the nearest wired keyboard is an overpriced one at BestBuy? If you find yourself in the same boat, you might find the trick in The Solution above to be just the thing for you.
The Case for a Virtual On-screen Keyboard
This situation made me realize the usefulness of on-screen virtual keyboards. It appears that this is not a feature that can be activated on Mac OS X before logging in, so it might be nice in the future.