This command makes the current page size the page size which will be used for new documents.
// Set PageSize (use smaller margins, 720 twips)
wpdllInt1.Memo.PageSize.SetPageWH(-1, -1, 720, 720, 720, 720);
// This should be also used for new documents
wpdllInt1.Memo.TextCommandStr(19, 0, "");