If you would like to get more familliar with VMKit here is a "toyVM" tutorial which contains.
A presentation introducing the general functionning of virtual machines
and the functionning of a virtual machine based on VMKit.
It also introduces the tutorial's proceeding. Download the presentation here.
A "mode of using" describing each step in the tutorial in order to develop
a minimal virtual machine based on VMKit components.
A base code canvas for starting developping the minimal virtual machine
(download the base code here).
You have to download and install VMKit first. See the Get Started page for more information.
You can download all the needed parts gathered in an archive here.