pre and post commands are NSH Scripts as you can see in:
as we are invoking
nexec -e <Pre Command>=<script>
I presume you could put in pre or post command something like:
cmd /c "echo . | powershell echo bladelogic" or cmd /c "echo . | powershell C:/ps_script.ps1"
I have not tested this but I presume it would work.
it starts a cmd on windows and sh on unix.