I compiled 2.6.10 kernel on a Slackware 10.1 box a few weeks ago and until now I had no problems. Yesterday I had to write a CD and the system just crashed (no response from mouse, keyboard..., just restart button). I noticed that with my old 2.4.29 kernel all works fine. With this new kernel I can erase CD_RW but just fast(not full) and when I want to write a CD (with k3b, or just cdrecord), after 15 second, the system crushes. I don't know what to do. I heard that with 2.6.* kernels it is not necessarily to use append = "hdc=ide-scsi" in lilo.conf.
How do I have to configure the kernel and other files in order to make my ASUS CDRW unit write CDs?
Thanks!

Most likely the ASUS CDRW is an ATA device. You're right, scsi-emulation is no longer needed for non-scsi devices. I have also had trouble not with not being able to write CDs/DVDs when not root with 2.6 kernels, which I think has been fixed.

Try doing seeing if you can write an iso image directly with
'cdrecord dev=ATAPI:0,0,0 <name of iso image>'

If that works, see what command k3b is using and tweak it.