In general, Bluetooth keyboards that you have paired with the Mac should work in the rEFIt menu. Since the EFI pre-boot environment (in which the rEFIt menu runs) is a separate operating environment from Mac OS X or Windows, the keyboard needs to reconnect after you enter the rEFIt menu. The keyboard needs to initiate the connection, which it only does after you press a key. Establishing the wireless connection can take a few seconds, and the first keypress may be lost.
During installation of Windows, Bluetooth support will be unavailable, and you need to use a USB or built-in keyboard. Once Windows and the Boot Camp drivers are installed, you can pair the Bluetooth keyboard in Windows and it should work normally. Apple also explains this in the Boot Camp FAQ.
You’ll likely have similar results with Linux, that is, the Bluetooth keyboard will only work once Linux is fully installed, and the keyboard has been paired with the Linux Bluetooth stack. Even then, it may not be possible to use the keyboard to make choices in the Linux boot menu (GRUB, LILO, etc.).
If you have problems with the wireless keyboard, there is nothing rEFIt can do about it. Use a USB keyboard or a built-in keyboard instead. See also Apple’s System requirements for Microsoft Windows support document.