#take a snapshot
xe vm-snapshot new-name-label= vm=
#convert back to a vm
xe template-param-set is-a-template=false uuid=
#export
xe vm-export vm=(newname) filename=
#cleanup-snapshot
xe vm-uninstall uuid=
from: http://serverfault.com/questions/489184/export-xenserver-snapshot-as-file-via-console