How to convert EXT3 ot EXT4 root (/) partition without access to the system or media drives?

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http://serverfault.com – We have a 'baremetal' VPS hosted server with our provider. Everything on this 'instance' is in one main root / parition. If I don't have access to this system, how can I convert this to an ext4 file system? is this even possible? This is running Ubuntu 10.04 kernel version 2.6.36 . thanks. (HowTos)