Changing WindowsXP Pro DOS-Mode Install Options

[svet-am]

i'm trying out different options for my HTPC. Right now I'm experimenting with SageTV 4.0 running under WinXP SP2. SageTV recommends 64k cluster sizes to reduce the overhead during video playback. By default, WinXP formats drives (during the DOS-mode portion of the install) with 3k cluster size. Is there a way to change this value to 64k during the install? This is my only drive, so I need to do this before I get Windows installed and have access to the GUI. thanks in advance for any insight