You can run a powershell script in the same general way that you would run a BAT script. Basically anything you can do on the command line as the SYSTEM account should work in actionscript, with a few rare exceptions.
I would not recommend including the powershell exe and I would not recommend uploading a PS1 file and downloading it to the clients to run in most cases. You can use the absolute path to powershell.exe but you can also dynamically query the absolute path using relevance, like the following:
See this: http://bigfix.me/fixlet/details/3860
waithidden { pathname of file ((it as string) of value "Path" of key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PowerShell\1\ShellIds\Microsoft.PowerShell" of native registry) } -ExecutionPolicy Bypass -File powershell.ps1
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