I've posted the Microsoft Lifecam standalone drivers a while ago and got a lot of questions regarding how I extracted them from the original setup. I'll explain it based on the latest 64bit installer for that webcam [LifeCam 3.0 downloaded here], but I'll also try to keep this short guide as general as possible. The same method works for all kinds of installers. I very often use it in cases where the driver installation is linked to some ugly software installation.
Often enough, you can easily extract the installer itself without even running it. WinRAR does a good job there, just right click the file and select WinRAR's extraction. Even more archive and installer formats are supported by Universal Extractor (open source).
In the case of the LifeCam software, WinRAR is able to extract the files, but that doesn't help us: The setup file does not contain the drivers directly, but will download them on installation. (you even need a network connection just to install the drivers...).
If you cannot extract the installer, or it doesn't contain the files you're looking for, run it. Most likely, it will extract (or, in our case, download) its files to a temporary location, not even requiring that you continue the installation from that point on. Look for a newly created folder in your temporary files (clean up before), or use a tool like Process Monitor to watch where it creates files.
The LifeCam installer requires you to confirm the usual EULA and will then download the necessary files to (in my case) %userprofile%\AppData\Local\Temp\LifeCamSetup (Win Vista). Leave the installer open, do not continue its dialogs. Find the file you're interested in and copy it somewhere else, or, if it is compressed, extract it. In our case, LifeCamx64.cab (a Microsoft archive format) contains the drivers we're interested in (in a subdirectory called "drivers64"). Copy them somewhere else, close the installer (it doesn't allow you to cancel it properly; kill the process setupstb.exe and remove the temporary files). Luckly, the .cab contains drivers for all models.