For the Oracle Linux 6, Update 4 OS, you can append the PXE label directly to the driver disk.
Label OEL6u4-LX507
Kernel OEL6u4-vmlinuz
append initrd=OEL6u4-initrd.img,OEL6u4-xsigo-rhdd-2.6.32-358.el6.x86_64-
5.0.7.LX-x86_64.img network