NTLM Authentication is supported through IIS, but not using JCIFS:
A custom NTLM authenticator is NOT supported but can be found as an attached "customauth-0.4.jar" file to this page:
There are several other attachments to these pages as well so you'll need to read the pages carefully to understand how to install everything. In addition, Authentication Configuration page is useful for determining which authentication approach is appropriate for you.
Note that the 5. NTLM Authenticator for Confluence, Comments 07-08 is a different authenticator. While it may work fine for you, it is not supported.