At the moment there is no possibility to make basis authentication.
This client appeared because I require a fast/convenient/low memory foot print client for
my numerical calculations. Therefore, I have not added all specifications to it. If you simply need a full client, no matter how slow it can go for large messages, you could better try suds.
On the other hand, I do not see any problem in adding such basic features to the library.
The library has a very simple structure and it should be very straightforward. Please let me know if you can add yourself, or at least tell me what kind of authentication you require. In the latter case I'll try to look into it in the next couple of weeks.