$Instance = 'ServerName'

     $scriptargs = [Microsoft.SqlServer.Replication.scriptoptions]::Creation `
            -bor  [Microsoft.SqlServer.Replication.scriptoptions]::IncludeArticles       `
            -bor  [Microsoft.SqlServer.Replication.scriptoptions]::IncludeGO`
            -bor [Microsoft.SqlServer.Replication.scriptoptions]::IncludeCreateSnapshotAgent`

 Get-ReplPublication $Instance | ForEach-Object { 
                               $script = Get-ReplScript $_  -scriptOpts $scriptargs
                               $script | out-file -filepath $FilePath -force; }