I haven't tried it, but you will probably have some trouble getting VirtualBox installed. As far as I can see there's no MyDSL extension, and there was no package for Debian Woody (the version of Debian with which DSL is compatible).
This means that you'll have to build it from source, and the dependency list (https://www.virtualbox.org/wiki/Linux%20build%20instructions) indicates that this will require first compiling a number of dependencies which are also not already available for DSL. QT 4 is likely to be difficult for one thing.
Whether it is possible or not will depend on whether one of the dependencies requires a later kernel than the 2.4.31 release used in DSL. If so, your only option might be to try to find an earlier version of VirtualBox that works with earlier releases of the problem dependency.