This was essentially the production of the queue simulation until Nov/2010. The "qsim" was then forked out for further development. Unfortunately, this fork was done somewhat too late, so "simulation" is not exactly the stable version that was used over many years, but something that is already somewhat modified, and was not used very much after that.  (Please let us know if you have problems.)

Note that you will get a "simulation" section in the log file even if you have selected a different mobsim (such as qsim or jdqsim).

There used to be an option to start an external mobsim.  This still seems to be there but the syntax is a bit awkward:

<module name="controler" >
   ...
   <param name="mobsim" value="null" />
</module>
<module name="simulation" >
   <param name="externalExe" value="<path-to-executable>" />
</module>

I.e. you need to specify that you are not using the (queue)Simulation, but then set a parameter inside the (queue)Simulation config block.