The old script was:
Dim oCatalog ' As COMAdmin.COMAdminCatalog
Dim sName 'As String
Dim sMachine 'As String
Set oCatalog = CreateObject("COMAdmin.COMAdminCatalog")
sName = "Tridion Content Manager"
sMachine = "tridionserver"
oCatalog.Connect sMachine
oCatalog.ShutdownApplication sName
And this became:
$TridionAppName = "Tridion Content Manager"
$TridionMachine = "tridionserver"
$comAdmin = New-Object -comobject COMAdmin.COMAdminCatalog
$comAdmin.Connect($TridionMachine)
$comAdmin.ShutdownApplication($TridionAppName)
(Just leave the line with the call to connect out to run this on your local machine).