Importing XenServer DDK 6.1 to XenServer 6.0.2 from XenCenter got stuck with message ‘Preparing to import vm’.

The workaround is to extract the DDK iso file to a NFS ISO storage. Attach that storage to your XenServer host and then import the file from there on the CLI:

xe vm-import filename=/var/run/sr-mount/a653a34e-ec0f-5134-906c-9077cafb8c9d/XS61DDK/ddk/ova.xml