WiX v3 has a feature I added a while back to support this scenario. It allows you to point at an admin image of your msi based install package. This will be very familiar to some of you who have used patchwiz and pcp's in the past. The difference here is that your patch authoring can be done using the WiX v3 Patch element and it follows the same workflow as patching a WiX v3 based msi after the first stage of creating the diffs.

Something I found really easy, and I could see this being used by smaller products who dont have a lot of infrastructure, is the ability to hand edit your admin image to product the patch. For example, I wanted to update a single file in my product:

1. I created an admin image
2. I made a copy of the admin image
3. I updated the loose file in my copy of the admin image

After running it through the series of command lines, I got a patch that updated the file. Pretty simple...

The command lines you need to run are all the same as the ones in my sample: Building a Patch using the new Patch Building System - Part 3. The only difference is that you need to pass the -ax command to torch with a path to extract embedded binaries to instead of the -xi switch and add the -xo to specify to create a wixmst instead of an mst. This tells torch that the input is admin image instead of xml. Also, specify the path to the msi in the admin images instead of the wixpdb as the target and upgrade. Everything after that should follow the same process.

Let me know how it works! :)

Bonus feature: One of the most useful things in the WiX v3 patching system is the ability to filter whats in your patch using patch families to only ship your customers the updates they need. This allows you to grab changes per Fragment from your wix source. When patching from admin images, there is no source so you would think that the filtering isn't suppoted. Not so! This was one of the more fun parts of this implementation. We "auto-fragment" the msi into what we consider to be the optimal chunks to give you the ability to filter if you choose to do so.

This was originally posted here and may have additional comments.