Copied From: http://forums.virtualbox.org/viewtopic.php?f=6&t=29695
Change Command + Q -> Command-Control-Option-Q and Command + H -> Command-Control-Option-H
defaults write org.virtualbox.app.VirtualBoxVM NSUserKeyEquivalents ‘{“Quit VirtualBox VM”=”@~^q”; “Hide VirtualBox VM” = “@~^h”;}’