Damn small linux is a tiny Linux. Because it uses very little resource, it is ideal for a virtual machine.
Read what to do here
Damn Small Linux uses a repository call MyDSL. I tried installing gcc1-with-libs.dsl and the kernelsource.dsl from mydsl. Unfortunately, the kernel source from the mydsl is a bit old.
To install, I would have to download the kernel for 4.0, then patch it with Knoppix patch. While this is not difficult, its rather too much work for getting guest additions to work.