Looks like you're missing some backslashes toward the bottom, so
virt-install wouldn't see anything past "os-variant". Here's mine
(adding the ttyS0 allows looking at it on the cli with "virsh console"
as well):
virt-install \
--name=myhost \
--connect qemu:///system \
--disk path=/data/virt/guest$$,size=20,bus=virtio \
--vcpus=2 --ram=1024 \
--graphics vnc,keymap=en-us \
--autostart \
--location=http://example.org/ks/el6/x86_64/ \
-x "console=ttyS0,115200
ks=http://example.org/ks/myhost.cfg" \
--network bridge=br0 \
--os-type=linux \
--os-variant=virtio26