Мне удалось выполнить то, что я хотел сделать, с помощью следующего кода:
/// <summary>
/// Adds item to archive
/// </summary>
/// <param name="item">Item to add</param>
/// <param name="destination">Archive path</param>
/// <param name="destination">web site of archive</param>
/// <returns>Result of arhivation process</returns>
public static string ArchiveItem(SPListItem item, string destination, SPWeb web)
{
// Save main meta information for later use:
var author = item.File.Author;
var modifiedBy = item.File.ModifiedBy;
var modified = item.File.TimeLastModified;
var created = item.File.TimeCreated;
// Get destination filename:
var destinationFile = destination + "/" + item.File.Name;
// Copy the item and set properties:
var coppiedFile = web.GetFolder(destination).Files.Add(destinationFile, item.File.OpenBinary(), author, modifiedBy, created, modified);
coppiedFile.Item["Created"] = created;
coppiedFile.Item["Modified"] = modified;
// Save changes, UpdateOverwriteVersion causes object to save without saving a new version.
coppiedFile.Item.UpdateOverwriteVersion();
// If moving is enabled, delete original item:
item.Delete();
return coppiedFile.ServerRelativeUrl;
}