Setting the Allocation Unit Size When Creating Partitions Using WSIM

Does anybody know if there any way to set the allocation unit size when setting up disks using an AutoUnattended.xml? This is for Windows Server 2012. The reason for doing so, is to be able to format the disks that will be used with SQL server with 64K bytes per cluster, without having to manually or use a script to format these once the OS install has completed. Thanks in advance.