add parm and more dynamic

 How can I add the parm of userid password for machines that need SQL authenication. In the script it passes in Server now I want 2 other pieces
a userid and password. If both blank use a trusted connection. The second piece would be to add a DateTime to the report and
store it in a Network folder like \\server\db_inventory\filename. I would like the script just to append new days actiivity to the report.

 Thanks.

#Create a new Excel object using COM 
$Excel = New-Object -ComObject Excel.Application
$Excel.visible = $True 
$Excel = $Excel.Workbooks.Add()
$Sheet = $Excel.Worksheets.Item(1)
$intRow = 1
 ForEach ($instance in Get-Content "C:\sql_servers.txt")
    {
    [System.Reflection.Assembly]::LoadWithPartialName('Microsoft.SqlServer.SMO') | out-null
    $s = New-Object ('Microsoft.SqlServer.Management.Smo.Server') $instance
    $dbs=$s.Databases
     $intRow++
     #Create column headers
     $Sheet.Cells.Item($intRow,1) = "Server: $s"
     $Sheet.Cells.Item($intRow,1).Font.Size = 12
     $Sheet.Cells.Item($intRow,1).Font.Bold = $True
     $intRow++
     $Sheet.Cells.Item($intRow,2) = "Database"
     $Sheet.Cells.Item($intRow,2).Font.Bold = $True
     $Sheet.Cells.Item($intRow,3) = "Data Name"
     $Sheet.Cells.Item($intRow,3).Font.Bold = $True
     $Sheet.Cells.Item($intRow,4) = "Data File"
     $Sheet.Cells.Item($intRow,4).Font.Bold = $True
     $sheet.Cells.Item($intRow,5) = "Data Size (MB)"
     $Sheet.Cells.Item($intRow,5).Font.Bold = $True
     $Sheet.Cells.Item($intRow,6) = "Data Used Space (MB)"
     $Sheet.Cells.Item($intRow,6).Font.Bold = $True
     $Sheet.Cells.Item($intRow,7) = "Log Name"
     $Sheet.Cells.Item($intRow,7).Font.Bold = $True
     $Sheet.Cells.Item($intRow,8) = "Log Size (MB)"
     $Sheet.Cells.Item($intRow,8).Font.Bold = $True
     $Sheet.Cells.Item($intRow,9) = "Log Used Space (MB)"
     $Sheet.Cells.Item($intRow,9).Font.Bold = $True
     $Sheet.Cells.Item($intRow,10) = "Log File"
     $Sheet.Cells.Item($intRow,10).Font.Bold = $True
    foreach ($db in $dbs) 
        {
          $dbname = $db.Name
          $fileGroups = $db.FileGroups
          ForEach ($fg in $fileGroups)
            {
       #   write-host $fg.files | select name
            If ($fg) 
                {
                    $intRow++
                    $mdfInfo = $fg.Files | Select Name, FileName, size, UsedSpace
                    $Sheet.Cells.Item($intRow,2) = $dbname
                    $Sheet.Cells.Item($intRow,3) = $mdfInfo.Name
                    $Sheet.Cells.Item($intRow,4) = $mdfInfo.FileName
                    $Sheet.Cells.Item($intRow,5) = ($mdfInfo.size / 1000)
                    $Sheet.Cells.Item($intRow,6) = ($mdfInfo.UsedSpace / 1000)
                    $logInfo = $db.LogFiles | Select Name, FileName, Size, UsedSpace
                    $Sheet.Cells.Item($intRow,7) = $logInfo.Name
                    $Sheet.Cells.Item($intRow,8) = ($logInfo.Size / 1000)
                    $Sheet.Cells.Item($intRow,9) = ($logInfo.UsedSpace / 1000)
                    $Sheet.Cells.Item($intRow,10) = $logInfo.FileName
                }
            }
        }
        $intRow++
    }
    $Sheet.UsedRange.EntireColumn.AutoFit()