if you want to do content approval automatically done for document libraries , here is the set of PowerShell commands
EnableModeration is the property that needs to set true.

$site = New-Object Microsoft.SharePoint.SPSite("http://mysite/TestSite")

foreach($web in in $site.AllWebs){

foreach($List in $web.Lists){

if(($List.BaseType –eq "Document Library" ){

$List.EnableModeration=$true

}

}

$web.Dispose()

}

$site.Dispose()
Hope it helps. Happy SharePointing :-)