Xen Shell
The Xen shell allows you to do a bunch of stuff to your VM that you wouldn't otherwise be able to do - for example, you can power up your VM if you accidentally type "sudo halt" or access the console in case your firewall locks you out.
Accessing the admin shell
ssh [vm-name].admin.xeriom.net -p 2202 -l [account_name]
You account name and your password are the same as you use to sign into Xit at http://xit.xeriom.net/. If you'd like to change your password please do so in Xit. You will have to reset your password at least once for this to work.
For example, if your account name is john_smith and you wanted to access the admin shell for a virtual machine called john-smith-01 you'd run the below command.
ssh john-smith-01.admin.xeriom.net -p 2202 -l john_smith
Setting up the Xen Shell
This is just so I can keep notes on how the Xen shell was setup on the physical hosts. If you're just trying to access the Xen shell you can stop reading now 
Ubuntu based hosts
sudo apt-get install xen-shell vnstat --yes
Gentoo based hosts
wget http://xen-tools.org/software/xen-shell/xen-shell-1.8.tar.gz tar -xzvf xen-shell-1.8.tar.gz cd xen-shell-1.8 sudo make install
Some customisation is required to make either xen-shell or xen-login-shell (I forget which) look under /var/vm/conf/*.conf for configuration.
Common
sudo visudo # Add these lines: User_Alias XENUSERS = %xen Cmnd_Alias XEN = /usr/sbin/xm XENUSERS ALL = NOPASSWD: XEN
Now follow the instructions to setup a CentralisedAuthentication client.
Make sure that /etc/passwd and /etc/group don't have %xen or any of the users -- this can cause weird error messages from the xen-shell about users not being in the sudoers file.
Finally, edit /etc/xen/*.cfg to include
xen_shell = 'username'
at the bottom of the file. TODO: Automate generation of these files.