I use the Logitech diNovo Edge. This keyboard is awesome and I love it. When the dongle is not initialized as a bluetooth device - ie in bios, boot, install etc it simply emulates a usb keyboard / mouse and works (without any fancy features) perfectly. Hence, it works in text mode great. This happens during during System Startup, BIOS access or during the actually Linux console startup sequence.
However, as soon as it is initialized as a bluetooth device it forces you to use bluetooth pairing to work (this applies to Windows too). So, as you can imagine, by the time I reach KDE the keyboard doesn't work.
A solutions I have found to this problem (Source http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=355497):
Edit with sudo (text-editor) /etc/default/bluetooth
Then look for the line that says:
and change it to this: