Getting VirtualBox to use Bootcamp partitioned Windows XP on a Mac

So, I really wanted VirtualBox to use the Bootcamp partitioned windows XP. After a bit of trauling I found this but had a slight error "resource_busy" and found this with a reply sorting it out. Turns out you have to unmount the disk to create the .vmkd file.

1. make a new machine
2. when asked about disks, load up the terminal
3. find the disk and partition with windows installed
1. diskutil list
4. unmount it
1. I did this in disk utility
5. change permissions on it
1. chmod 777 /dev/diskXsY  (replace X and Y with numbers)
6. go into the folder where your new VirtualBox machine is
1. cd ~/VirtualBox\ VMs/VirtualComputerName
7. make the .vmkd file
1. sudo vboxmanage internalcommands createrawvmdk -rawdisk /dev/disk0 -filename "winXP.vmdk" -partitions 3
2. you have to find out how many partitions are on the harddrive. I've got 3
8. change permissions of the files created
1. chmod 777 winXP*
9. in VirtualBox, select the disk file you created.

Sorted.

Turns out the error I got was from not reading the bit where you have to unmount it.