Virtualbox portable inside winPE: HELP Please!!!

Hello @all,

I'm quite stuck here for some time and am trying my luck here now.
Goal: I want to PXE boot Student laptops into a WINPE with just virtualbox inside. From there I can mount a readonly VHD over the network and use different OSes for my classroom.
I was trying to build a small Linux LiveCD but I cant get EFI Laptops to boot.
My actual status: I can PXE Boot into a standard winPE created from WIN10. I have setup a ISC dhcp Server with ipxe which sends the laptops to either BIOS version or EFI version. I can even boot Macbooks (It took me a long time to modify my DHCP Server to act as Apple netboot Server) with this system.
So right now I can boot a small boot.wim without problems.

I'm stuck in putting apps into the WIM. I tried a lot of different versions and I tried even to work with vbox.me which offers a portable Virtualbox solution.
Anyway: Maybe someone can help me out here.

So the workflow would be:
1. boot via PXE into winPE (BIOS, UEFI and EFI) (works already)
2. create a SMB connection to a server (works already)
3. wget a file from a webserver and execute it (works already)
4. start virtualbox with VHD via SMB (STUCK Need HELP PLEASE)

This solution allows me to use the student laptops for education and don't have to care how many viruses are on their machines. I just PXE boot into a System of choice and start my lesson.

Thanks for your help!!!

Gerald