No it is not possible directly from the CreateFolder method. However, you can use combination of methods SendCommand and ReadResponse.
// Send CREATE command with custom parameters
imap.SendCommand("CREATE", "param1", "param2", ..., "paramN");
ImapResponse response = imap.ReadResponse();
// display server response
foreach (ImapResponseLine line in response.GetLines())
{
Console.WriteLine(line.Raw);
}