CentOS - Mar 2016 - making a new initrd

Hi,

I built a new kernel for C7 that contains the required driver for a new 
motherboard we have here.

I'd like to take this initramfs and rebuild it/modify it so that it is 
suitable for pxe booting.

I have tried

dracut -v  --force --add "anaconda" initramfs.img  # results in an
image
that is too large for tftp

Or

dracut --nofscks --nomdadmconf --nolvmconf --xz --no-early-microcode -m 
"anaconda"  --force initramfs.img # kernel panics

What steps should I be taking to create an initrd image suitable for pxe 
boot ?

Thanks