From MEPIS Documentation Wiki
kvm, Kernel-based Virtual Machine is a Linux kernel virtualization infrastructure
By itself, KVM does not perform any emulation. Instead, a user-space program uses the /dev/kvm interface to set up the guest VM's address space, feeds it simulated I/O and maps its video display back onto the host's. At least two programs exploit this feature: kvm, a modified version of Qemu and Qemu itself since version 0.10.0
Installing and configuring kvm
1. Install the user-space program
apt-get install kvm
2. Add your user name to kvm group (edit /etc/group file or use a GUI like KUser)
3. Log out and log back in.
You could boot a Live CD with kvm like this:
kvm -cdrom filename.iso
or, if you want to specify the amount of memory allocated for the virtual machine (for example allocating 1GB):
kvm -cdrom filename.iso -m 1024
More info and options are available in man pages "man kvm" and "man qemu".