I have yet to figure out if it can be made to work, but i have only just purchased the most current model wireless keyboard and i am also using version 10.5.8 (on an old G5 powerpc which was updated from 10.4 a while back) but when i made the purchase i noticed that it states:
Minimum System Requirements
- Bluetooth-enabled Mac computer with Mac OS X v10.6.8 or later and existing keyboard and mouse for initial setup
so, it may not be able to work completely with older OS version like 10.5.8.
however, 'code is only code', there maybe a way. i ordered it by mail and it should arrive in a few days so i will do some work and see what i can find. im not a programmer myself but i have some experience with keyboard mappings and functions of this nature. if discover anything useful i will update you.
I am afraid not. I have played around with the keyboard quite a lot. It mostly works but the special function buttons do not work. some of them do different things and others do nothing. unfortunately i do not have the programming background to write my own driver for this, so i think i am out of luck. sorry i dont have better news... perhaps someone will figure something out but probably our systems are too old for that many people to put effort into it at this point. good luck!
The 10.6 Snow Leopard DVD is back in the Apple online store. You can get it for $19.99. You will need to be running 10.6.8 to access the App Store to order Lion or Mountain Lion. http://store.apple.com/us/product/MC573/mac-os-x-106-snow-leopard