tl;dr: ubuntu-kernel-for-acer-c7.sh. Works for Ubuntu 12.04 and Ubuntu 12.10.
I followed Jay Lee's instructions and installed ChrUbuntu on my Acer C7 Chromebook, after having upgraded the RAM and replaced the hard drive with an SSD.
Out of curiosity, I run the command kvm-ok, which reported that the machine was able to make use of the KVM extensions:
Then I proceed to install VirtualBox itself. Part of the installation process involves compiling and installing the host kernel modules. The process failed because no suitable kernel headers could be found on the system.
I then followed olofg's instructions in order to create Ubuntu packages for linux-image and linux-headers. The process finished successfully, but now kvm-ok reported that KVM extensions were not supported on the system.
It turns out that by adding the parameter disablevmx=offto the kernel command line, the KVM extensions are supported.
I've compiled a shell script, based on olofg's instructions which updates the boot partition with a KVM-enabled kernel, and installs the generated Ubuntu kernel packages (kernel image and headers), so that compiling VirtualBox kernel modules is possible: