Download latest Service Pack for ProLiant ISO and md5 sum.

Verify download.

$ cat HP_Service...iso.md5sum 
0203aaaaf7dd3670507e4f25056c6758 *SPP2014060.2014_0618.4.iso

$ md5sum HP_Service...iso 
0203aaaaf7dd3670507e4f25056c6758  SPP2014060.2014_0618.4.iso

Mount ISO to extract kernel and initrd images.

sudo mount -o loop ./SPP2014060.2014_0618.4.iso ./mnt/

Copy images from pxe/spp2014060 to tftpboot directory.

/var/lib/tftpboot/images/spp2014060/
/var/lib/tftpboot/images/spp2014060/spp2014060.menu
/var/lib/tftpboot/images/spp2014060/vmlinuz
/var/lib/tftpboot/images/spp2014060/initrd.img

Add HP SPP to PXE menu.

LABEL HP SPP 2014.06.0
        MENU LABEL HP Interactive Firmware Update Version 2014.06.0
        kernel /images/spp2014020b/vmlinuz
        append initrd=/images/spp2014060/initrd.img media=net root=/dev/ram0 ramdisk_size=1105536 init=/bin/init loglevel=3 ide=nodma ide=noraid nopat ip=dhcp pnpbios=off vga=791 splash=silent hp_fibre showopts noexec32=off numa=off nox2apic TYPE=MANUAL AUTOPOWEROFFONSUCCESS=no iso1=nfs://1.2.3.4/nfsshare/HP_Service_Pack_for_Proliant_SPP2014020B.2014_0421.2_780345_001_spp_2014.02.0B-SPP2014020B.2014_0421.2.iso iso1mnt=/mnt/bootdevice pci=bfsort
        ipappend 2