git clone git://github.com/rraf/edk2.git
cd edk2
git clone git://github.com/rraf/Ext2Pkg.git

build BaseTools, set environment, set target, add Ext2Pkg to OvmfPkg

build OvmfPkg http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=How_to_build_OVMF

in the folder where you copied the bios/video image.

qemu-img create -f raw disk.img 100M
mkfs.ext2 -F disk.img 
qemu -L . -hda disk.img -serial stdio

Enjoy.