The easiest way would be to finish the LabVIEW installation, then download NI-USRP 1.2 from NI.com/updates and run that installer. It will install support for the USRP into LabVIEW.
The LabVIEW installer usually asks you to point it at something called the Device Drivers DVD, but it's not a requirement for LabVIEW installation, especially if that DVD is not handy. NI.com/updates had all the installers for the various hardware support, so you can install at your leisure and as needed.
