We're just switching our images over from good old ghost .GHO's to .WIM format. One of the reasons is that we have heard that software updates could be modified/installed in .WIM's offline.
For example, right now if we wanted to move from Adobe Reader X to Adobe Reader XI, we would need to drop our base, uninstall Reader X, install Reader XI, reseal our sysprep'd image, then recapture in Ghost.
Unfortunately the only process I can find looks like it only applies to Windows Updates. Other walkthroughs I've found show how to deploy the software as part of a task sequence in SCCM which I don't have access to and our customer does not actually have the network infrastructure to support.
Is this possible or did we misunderstand the scope of the offline updating feature?
Ultimately a WIM file is just a type of disk image format. The tools available from Microsoft to manipulate a WIM offline basically amount to mounting the image, making changes to the files inside, and unmounting the image while committing the changes. There are some additional features that allow you to pre-install drivers and Microsoft hotfixes or service packs. But there's no real way to run a typical application installer against the mounted WIM file.
If you know exactly what the installer intended to to, you could hypothetically make the filesystem changes necessary and modify the registry using an offline registry editor. But it's probably more trouble than it's worth.
Most people use WIMs in conjunction with Windows deployment tools like MDT (Microsoft Deployment Toolkit) and SCCM as you previously mentioned. MDT is actually free, much lighter weight than SCCM, and supports the same sort of task sequences as SCCM.