Fedora xen - Apr 2007 - Building a kernel module for Xen for Fedora 6 Xen kernel

Hello,
 I downloaded the dm-userspace sources from
 http://static.danplanet.com/dm-userspace/

 (By hg clone).

 Now I want to build this module.

 I run Fedora 6 xen kernel (2.6.18-1.2798.fc6xen).
 I have kernel-xen-devel-2.6.18-1.2798.fc6 and kernel-xen-2.6.18-1.2798.fc6
installed, and also xen-3.0.3-8.fc6 and xen-libs-3.0.3-8.fc6.

Building the dm-userspace should be against sources of the kernel;
it uses header files from drivers/md tree ; this header files are
**NOT** part of the kernel-xen-devel rpm (which **DOES** include headers from
include/linux).

What should I do?

In the fedora download site, there is no SRPM for kernel-xen. There is
SRPM for 2.6.18 kernel (kernel-2.6.18-1.2798.fc6.src.rpm); is it good for
building a Xen kernel module ? should I use it ?
There is also src rpm for xen (xen-3.0.3-0.1.rc3.src.rpm) but this
seems irrelevant.

Any ideas?
Ian