You will have to contact NI for it. Here's the note from the FTP site where it's located:
"This release of Lookout 4.0.1 (build 61) is contained in the zip file called lk401b61_dev.zip. This file is password protected. In order to receive the password from us, you will need to call customer support. The password will only be given out to customers who are entitled to this upgrade.
Lookout 4.0.1 build 61 contains bug fixes to 4.0.1 build 51."