Linux – How to update the kernel from 2.6.16 on Debian squeeze

I just did an update of my Debian system on my vserver from lenny to squeeze as described here.

I got some errors during the install, saying that glibc couldn't be updated.

I did an apt-get -f install, which gives me the following warning:

WARNING: this version of the GNU libc requires kernel version
2.6.18 or later. Please upgrade your kernel before installing
glibc.

The installation of a 2.6 kernel could ask you to install a new libc
first, this is NOT a bug, and should NOT be reported. In that case,
please add lenny sources to your /etc/apt/sources.list and run:
apt-get install -t lenny linux-image-2.6
Then reboot into this new kernel, and proceed with your upgrade

dpkg: error processing /var/cache/apt/archives/libc6_2.10.2-2_i386.deb (–unpack):
subprocess new pre-installation script returned error exit status 1
Errors were encountered while processing:
/var/cache/apt/archives/libc6_2.10.2-2_i386.deb

I added these lines to my /etc/apt/sources.list:

deb http://ftp.de.debian.org/debian squeeze main contrib non-free
deb http://ftp.de.debian.org/debian-volatile squeeze/volatile main contrib non-free
deb http://ftp.de.debian.org/debian-security squeeze/updates main contrib non-free

deb http://ftp.de.debian.org/debian lenny main contrib non-free
deb http://ftp.de.debian.org/debian-volatile lenny/volatile main contrib non-free
deb http://ftp.de.debian.org/debian-security lenny/updates main contrib non-free

Now I tried to install a newer kernel using this command:

apt-get install linux-image-2.6-openvz-686

Which leads to this error:

The following packages have unmet dependencies:
  libc-bin: Breaks: libc6 (< 2.10) but 2.7-18lenny2 is to be installed
  linux-image-2.6-openvz-686: Depends: linux-image-2.6.26-2-openvz-686 
  but it is not going to be installed
  locales: Depends: glibc-2.10-1
  nscd: Depends: libc6 (> 2.10) but 2.7-18lenny2 is to be installed

Question:

What do I have to do to upgrade my kernel?