The easiest thing might be to check out the latest VirtualBox build by downloading it over BitTorrent:
Once you download it:
- Decompress the VDI image.
Create a new VirtualBox VM.
If you want to duplicate the DreamPlug experience, make sure to give it 512 MB RAM.
- When it asks you about a "Virtual Hard Disk" select the .vdi file you extracted from the archive.
Make sure to go into your VM's settings and check the "Enable PAE/NX" box in the [System] -> [Processor] screen.
That should be enough to let you boot the VM.
You can log in as the superuser or a regular user:
As the names imply, the root user is the superuser, the fbx user is the normal user, and the plinth user is the box's system and self-maintenance user.
See the Beta Release TODOs.