It may be possible if you change your view on the folder settings to View Hidden Files and Folders, Found at: My Computer >> Tools >> Folder Options >> View Tab >> select view hidden files and folders.
Once thats done look in the root of your hard disks just by double clicking on the drive in my computer, you may then see I folder that wasnt there before, it will be a paler / whiter shade of yellow compared to the other folders and will be called something begining with WU, maybe WUTemp or WUCache something like that.
If you are able to find a folder like that, this will be where the updates are downloaded to before they are installed.
Although to be honest if you are running out of disk space on the download stage you may struggle to install it as its quite a hefty update once it extracts itself during the install process.
Hope this helps.
Chris