I was finally able to find a workaround:
Even though Mac OS X includes support for WebDAV folders, it does not work in conjunction with NTLM authentication and Netapp's Ontap software. A workaround is to use WDFS, which is an alternative WebDAV package for FUSE.
First, you must install Macports from http://www.macports.org/
Next, install xcode from https://developer.apple.com/technologies/tools/
Once this is all done, you need to open Terminal, located in Applications/Utilities. Once open, the first task is to install Fuse4x, Neon and Glib2, which WDFS uses as libraries.
Apply the follwing bold commands in the terminal window:
mac:~ User$ sudo port install fuse4x
mac:~ User$ sudo port install neon
mac:~ User$ sudo port install glib2
Once the packages are installed, download WDFS from http://noedler.de/projekte/wdfs/. Extract the archive to a folder, and then browse to that folder in Terminal using the ‘cd’ command.
mac:~ User$ cd Downloads/wdfs-1.4.2
We now need to compile WDFS by tying the following bold text in Terminal:
mac:wdfs-1.4.2 User$ sudo ./configure
mac:wdfs-1.4.2 User$ sudo make
mac:wdfs-1.4.2 User$ sudo make install
Once this is done, WDFS is installed and ready to use. Now you can mount the WebDAV share using the following commands in bold:
mac:Documents User$ cd ../..
mac:Users User$ cd User/Documents/
mac:Documents User$ mkdir WebDAV_Volumes
mac:Documents User$ cd WebDAV_Volumes/
mac:WebDAV_Volumes User$ mkdir WebDAVShare
This creates a folder which we can use as a mountpoint for the WebDAV share.
Now, to mount the share volume type the following command in the terminal:
mac:WebDAV_Volumes User$ wdfs http://[host]:80 /Users/User/Documents/WebDAV_Volumes/WebDAVShare/ -u "Domain\username" -p password -o accept_sslcert
The folder which previously appeared as WebDAVShare is changed to fuse4x volume 0 (wdfs) and can be used with read/execute permissions using the Mac OS X integrate Finder application. Writing to the volume using Finder where unsuccessful during my tests.
In order to be able to write to a WebDAV volume, you need to download and install a free third-party application called Mu Commander, located at http://www.mucommander.com/. Note: Attempts to use another popular free third-party application called X-folders where unsuccessful when trying to copy files to the new volume.
In any case, once Mu Commander is installed, you can browse to the fuse4x volume in one window with read/write permissions. You can now freely copy files between your newly created volume and your local system using WebDAV.