To let everyone start building VyOS instantly without spending time on build environment preparation, I created a ready to use VM.
Just login with vfactory/vfactory user and start (read the MOTD).
You can download the image here: http://so3group.net/downloads/vfactory/
It has two network cards, one NAT, and one host-only. The host-only one is unconfigured, so configure it according to your needs. SSH is enabled by default.
It should just work, but I can’t guarantee I didn’t miss anything, so let me know if something doesn’t work.