We had a requirement to add Copy/Paste icons the RadFileExplorer toolbar. That was the easy part. Getting them to call into the native Copy/Paste functions that are used by the Context Menus proved to be challenge.

Support provided me the solution below but it would have been nice to have OOB:

			function CopyFiles() {
				var fileExplorer = $find("<%=RadFileExplorer1.ClientID%>");
				fileExplorer.copyItems(fileExplorer.get_selectedItems());
			}
			function PasteFiles() {
				var fileExplorer = $find("<%=RadFileExplorer1.ClientID%>");
				fileExplorer.paste(fileExplorer._getCurrentFolderItem())
			}