First, start powershell
C:\Users\tester>powershell
Windows PowerShell
Copyright (C) 2009 Microsoft Corporation. All rights reserved.
Next, create remote sesssion
PS C:\Users\tester> Enter-PSSession -ComputerName testserver
Then, set command variables
[testserver]: PS C:\Users\tester\Documents> $tool="ipconfig.exe"
[testserver]: PS C:\Users\tester\Documents> $cmdLine = "/all"
Finally, invoke the command
[testserver]: PS C:\Users\tester\Documents> Invoke-Expression "$tool $cmdLine"