I was kickstarting a machine that needed two disks. The requirement was that the second disk was to be used as whole for LVM. It seemed there was no way to do so, but apparently there is. The snippet below makes it happen. The key part is –onpart=sdb.
part pv.02 --grow --size=1 --onpart=sdb
volgroup vg_data --pesize=4096 pv.02
logvol /data --fstype=xfs --name=lv_data --vgname=vg_data --grow --size=1