Note: since GNU Mach doesn't handle PAE, you need a PAE-disabled Hypervisor.

- Copy `gnumach-xen` and `hurd-modules` to your dom0 /boot.
- Copy `hurd` into `/etc/xen`, edit it for fixing access to your hurd / and swap
- Run `xm create -c hurd`, gnumach should get started.
- If `xm` complains about networking, it's Xen fault, see Xen documentation for how to configure the network. The simplest way is network-bridge with fixed IPs.

If you want to generate these images, first get the `gnumach-1-branch-Xen-branch` branch from gnumach CVS.
Then look for "Ugly" in `kern/bootstrap.c`, how to generate `hurd-modules` is explained there, and you'll have to fix `EXT2FS_SIZE` and `LD_SO_SIZE` by hand.
Then use

    ./configure --enable-platform=xen
    make

Instead, you can get the binaries at <http://dept-info.labri.fr/~thibault/hurd-xen/>.

The current `hurd-modules` was built from the debian packages `hurd 20070606-2` and `libc0.3 2.6.1-1`.