slapping some stuff around...
cd /tmp/newiso/ && xorriso -as mkisofs -r \
-V "HN-Specs-TC64 UEFI" \
-o efitest.iso \
-isohybrid-mbr boot/isolinux/isohdpfx.bin \
-J -joliet-long \
-c boot/isolinux/boot.cat \
-b boot/isolinux/isolinux.bin \
-boot-load-size 4 -boot-info-table -no-emul-boot \
-eltorito-alt-boot -e "EFI/BOOT/efiboot.img" -no-emul-boot \
-isohybrid-gpt-basdat \
/tmp/newiso/
appears to at least boot; i think i need to change my scripts n stuff to use the x86_64 packages now
for boot/isolinux/isohdpfx.bin is just grabbed from ubuntu package isolinux and plopped it there.