qemu-img create -f qcow2 omni.img 4g
cp /usr/share/qemu/edk2-i386-vars.fd .
qemu-system-x86_64 -smbios type=0,uefi=on -m 2g -cpu max -M q35 -drive if=pflash,format=raw,unit=0,readonly=on,file=/usr/share/qemu/edk2-x86_64-code.fd -drive if=pflash,format=raw,unit=1,file=./edk2-i386-vars.fd,readonly=off -boot order=cd,menu=on -rtc base=utc -device pci-serial-4x -device ich9-intel-hda -device hda-output,audiodev=snd0 -device AC97,audiodev=snd0 -audiodev pa,id=snd0  -vga vmware -device igb,netdev=net0,mac=52:54:00:12:34:31 -netdev tap,ifname=tap10,id=net0,script=no,downscript=no  -hda omni.img  -cdrom /var/tmp/omnios-r151052b.iso -serial pty -daemonize

Change audio, network for your setup. Remove ISO image after install. Make
sure your EFI vars file is present and writable. e1000 network doesn't work.