A Great little article on how to add a hard drive on a linux based Guest OS, without actually booting it. I knew this was possible but it saved me the hassle of experiementing on my own process!
Article is here:
www.cyberciti.biz/tips/vmware-add-a-new-hard-disk-without-rebooting-guest.html
The bits after the rescan , I used system-config-lvm (i.e Fedora/RH based OSes) as we have different requirements to create extra LVM partitions.
Neat!