my exact requirement..is to mount (ESX4) VMFS3 file system Storage LUN from Win2k3 server connected in same SAN group and access all HDK files as flat file, which can be backed up as flat file in local disk or any repository...simply wanted to use any free utility/solution to get the job done.
To access a VMFS partition you'd need an appropriate driver (see e.g. http://code.google.com/p/vmfs/). Anyway, you should be aware of all the possible issues. Firstly - and most important - DON'T present the LUN to the Windows host with write access or you will most likely end up with an unusable datastore, because Windows likes to resignature "unknown" partitions (change the partition type to NTFS). Secondly, to be able to access the files, the VM's have to either be powered off or you need to create a snapshot to be able to access the base disk.
Rather than doing something like this I'd suggest you take a look at http://communities.vmware.com/docs/DOC-8760