Since there was no sysresccd with current ZoL 0.6.5.2 modules available I looked around for an alternative.
At http://voidmain.is-a-geek.net/redhat/fe ... cking.html I found a recipe for a custom Fedora-Live-CD.

Follow these steps to create a ZFS-Live-CD:
(I used a Fedora-Live-Xfce-x86_64-21-5.iso I had at hand on my Fedora 21 WS)

Start with a new working directory

mkdir Fedora-Live
cd Fedora-Live

Unpack the Fedora-Live ISO

mkdir iso
mount -o ro,loop Fedora-Live.iso iso
mkdir source
cp -a iso/* source
umount iso

Extract the embedded ext-FS

unsquashfs source/LiveOS/squashfs.img

Extend the ext-FS. Alternatively remove unneded packages inside the chroot. See below.

truncate -s4G squashfs-root/LiveOS/ext3fs.img
resize2fs squashfs-root/LiveOS/ext3fs.img

Mount the ext-FS to chroot into it

mkdir ext3fs
mount -o loop squashfs-root/LiveOS/ext3fs.img ext3fs
mount -o bind /proc ext3fs/proc
mount -o bind /dev ext3fs/dev
mount -o bind /sys ext3fs/sys
cp /etc/resolv.conf ext3fs/etc/
chroot ext3fs

I did remove a bunch of unneeded packages and unused leave packages instead of extending the fs.
One could of course remove even more packages (or single files) to make the system fit on a 512MB stick.

yum erase -y xf* *font* web* *theme* xorg* *gtk* gst* mesa* selinux* trans* tele* pulse* esp*
while package-cleanup --quiet --leaves --exclude-bin | xargs yum remove -y; do true ; done

The ZFS install is straight forward.

yum install -y http://archive.zfsonlinux.org/fedora/zfs-release$(rpm -E %dist).noarch.rpm
yum install -y zfs kernel-devel-$(rpm -q kernel --qf '%{VERSION}-%{RELEASE}.%{ARCH}\n')
dkms status

Exit from the chroot

exit

Copy your current locale settings

cp /etc/vconsole.conf ext3fs/etc/
cp /etc/locale.conf ext3fs/etc/
cp -P /etc/localtime ext3fs/etc/

Instruct getty to autologin root

vi ext3fs/lib/systemd/system/getty@.service

  ExecStart=-/sbin/agetty --autologin root --noclear %I $TERM

Clean the unused space for better compression

dd if=/dev/zero bs=128k of=ext3fs/zero
sync
rm -f ext3fs/zero

Unmount the ext-FS and make the squashfs

umount ext3fs/sys
umount ext3fs/proc
umount ext3fs/dev
umount ext3fs
mksquashfs squashfs-root source/LiveOS/squashfs.img -noappend

Update the isolinux configuration with a new cd label, add selinux=0 and remove quiet and rhgb

vi source/isolinux/isolinux.cfg

   CDLABEL=ZFS-Live selinux=0

vi source/EFI/BOOT/grub.cfg

   LABEL=ZFS-Live selinux=0

Make the new ISO

mkisofs -o ZFS-Live.iso -J -r -hide-rr-moved -hide-joliet-trans-tbl -V ZFS-Live -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table source

Burn to CD or copy to usb flash

livecd-iso-to-disk --format --label ZFS-Live ZFS-Live.iso /dev/sd?-of-your-usb-disk

Done.