I avoid using COM objects whenever I can. One of the annoyances is that you need to look up the value of constants. Shay Levy, in http://www.powershellmagazine.com/2013/03/20/pstip-working-with-excel-constants/ has a script which demonstrates how to enumerate the constants for the Excel COM object. Get-COMConstants.ps1, is an advanced function generalization, which can be used for any COM object. The function contains a number of examples, such as this, which shows the constant names and values, and sends the selected constant value to the clipboard.
#Get the Constants for Excel, show results in Gridview, selected value goes to clipboard # create Excel object $xl = New-Object -ComObject Excel.Application $XLConstants = Get-ComConstants $xl $List= $XLConstants | Get-Member -m Properties | Foreach {[PSCustomObject]@{Constant = $_.Name;Value= ($XLConstants.[string]$_.name).value__}} $List|ogv -title "Pick a Constant" -PassThru | select -ExpandProperty value | clip