If you want to unlock the router from Sky then you will have to flash it with the firmware for the DG834gv3, available from
HERE
The files your are seeking are included in the full
GPL code. James very kindly removed the actual firmware and made it available separately. As he explained above it is no longer required to obtain the user/password which was the original reason for it's use and has been removed. You may have to download the full file if you really need it and it is quite large.
The image file you will need to 'trick' the router, as explained in Post 3 of this thread, will be on the Sky CD. You do not need to install it, just open it in Explorer and you will find it. Sorry, I don't know how you would do this on a Mac, but if you have access to a Windows XP machine it will be easily found.