The way I got around this problem running Slackware was set up my user with all root permission in the sudoers file. Then just ran k3b - " sudo k3b " from the command line. All was fine after that.
I didn't want to get to deep into the sudoers file, so I just edited the examples.
# User privilege specification
root ALL=(ALL) ALL
# Uncomment to allow people in group wheel to run all commands
%users ALL=(ALL) ALL
# Same thing without a password
%users ALL=(ALL) NOPASSWD: ALL
I don't know how safe that is, but it seemed to work for me. Just aslong as your users belongs to the users group, which it most likely will, you should be fine.
To fix you ATAPI problem, just enable scsi-emulation for you burner/cdrom. I have only done this with lilo and not sure how to do it with grub.
Edit your lilo.conf with should be /etc/lilo.conf and add an append line.
(note: replace hdc with with your burning or reding device)
If you need to do mulitple drivers, then;
(This is taken from my lilo.conf)
Once that is done, reboot and run k3b again. It shouldn't complain about any errors.
Once in k3b, goto 'Settings > Configure k3b...' Then select 'Devices' down the left hand side. Take note that your device's have now changed from /dev/hdb or /dev/hdc to /dev/sr0 or sr1 etc...
If you use the /dev/cdrom symlink, this will need to be changed. As root, cd to your /dev and do a 'ls -l cdrom'
You should see something along the lines of;
root@localhost:/dev# ls -l cdrom
lrwxrwxrwx 1 root root 8 Feb 16 00:00 cdrom -> /dev/hdb
Now all you have to do is;
ln -s /dev/sr0 cdrom
(note: Change sr0 to you cdrom)