I was given this "wrapper" script from Bill Robinson years ago and never thought to share it until now. Sorry for the delay.
Basically if you take this .NSH wrapper and add your powershell script at the bottom, you will be able to create PS scripts and use them native within BladeLogic for Extended Objects.
In the E.O. important things to note:
Command = nsh -c "??EO_LOCATION??/script_name.nsh ??TARGET.NAME??"
You will have to play around with the grammar file, but I use /etc/auto_*file grammar (auto.gm) and add Write-Host lines in the powershell script to make the format work with this type of grammar file.