start on filling in README missing pieces

diff -urN xen-unstable-0615/README niv-unstable-0615/README
@@ -79,3 +79,62 @@
 
 [NB. Unless noted otherwise, all the following steps should be
 performed with root privileges.]
+
+1. Download and untar the source tarball file. This will be a
+   file named xen-unstable-src.tgz, or xen-$version-src.tgz.
+   You can also pull the current version from the SCMS
+   that is being used (Bitkeeper, scheduled to change shortly).
+
+       # tar xzf xen-unstable-src.tgz
+
+   Assuming you are using the unstable tree, this will
+   untar into xen-unstable. The rest of the instructions
+   use the unstable tree as an example, substitute the
+   version for unstable.
+
+2. cd to xen-unstable (or whatever you sensibly rename it to).
+   The Linux (2.4 and 2.6), netbsd and freebsd kernel source
+   trees are in the $os-$version-xen-sparse directories.
+
+On Linux:
+
+3. For the very first build, or if you want to destroy existing
+   .configs and build trees, perform the following steps:
+       1. make world
+       2. make install
+
+   This will create the directories linux-2.6.11-dom0/ and
+   linux-2.6.11-domU/ after first cleaning everything. It will
+   create and install into the dist/ directory which is the
+   default install location. It will build the xen binary
+   (xen.gz), the boot images for dom0 and an unpriviledged
+   guest kernel (vmlinuz-2.6.11-xen0 and vmlinuz-2.6.11-xenU
+   respectively), the tools and the documentation.
+
+4. To rebuild an existing tree without modifying the config:
+       1. make dist
+
+   This will build and install xen, kernels, tools, and
+   docs into the local dist/ directory.
+
+5. To rebuild a kernel with a modified config:
+       1. cd linux-2.6.11-xen0         # or linux-2.6.11-xenU
+       2. make ARCH=xen menuconfig     # or xconfig
+       3. cd ..
+       4. make dist
+       5. make install
+
+   You can copy your own config into linux-2.6.11-xen0 first.
+   Alternatively, you can also copy your config file to
+   dist/install/boot/config-$version-xen0/U.  This is picked up
+   when a make dist is done. Include the ARCH=xen directive for
+   all make commands when building the kernels.
+
+6. To see a full list of targets and a brief description, type:
+       # make help
+
+7. Edit your grub.conf file as described above to have an
+   appropriate entry for your new kernel.
+
+
+