Booting virtual machine in Xen from DVD ISO

[Ryan Golhar]

I'm running RHEL5 with the Xen kernel.  This box hosts multiple virtual 
machines.  I've always had the DVD present when building the VMs in the 
past and the install initiated on its own.  This time, I build the 
machine, turned it off, obtained the DVD ISO, mounted the ISO, and 
booted the machine, but the machine insists on booting from the 
harddrive, even though its blank.

How do I force the VM to boot from the DVD ISO?  When I mount the DVD 
ISO, I see the dropdown box for the "Path to install media", but I'm not 
using an actual DVD...

Ryan