I have resolved this problem as well! However I now need to automate the process. Here's how it went...
I started out just imaging a machine and putting the AUTOUNATTEND.XML file in a folder, and then run recovery. It always ignored it. After about a week of head scratching, I finally decided to do a little research. Google and MS Social were basically dead ends, likely because I was approaching it from a different angle as those guys and the OP here. I then did a couple of things:
1. I mounted the winre.wim from my workstation with DISM.
2. I looked at the WINPESHL.INI and found it uses RECENV.EXE as the shell.
3. I opened RECENV.EXE in a string viewer (in my case, the demo of PE Explorer which expires in 4 days)
4. I saw that it looks for x:\unattend.xml, there is no XML file in the offline image.
5. I boot a PC to WinRE and open command prompt. Sure enough, the XML file is there.
6. I replaced the file with my custom one and ran recovery. It worked!
However I used Notepad that is in WinRE (and WinPE) to replace the file, but that is not a good automated way of doing it! These next steps, I have not tried them yet, I will tomorrow... First thing you want to look at is this link:
http://technet.micro...28WS.10%29.aspx
What we can do here is use FactoryRecoveryTool to reinstall the image for us. You will need to use the info from the unattend.xml that RECENV created when you got there, because it uses pathing and such. Then we can just call setup as such:
X:\SOURCES\SETUP.EXE /UNATTEND:X:\SOURCES\UNATTEND.XML
So if we use the /UNATTEND switch, you can put your unattend file anywhere you want and name it anything you want to. If you look in the WinRE.WIM you will find 2 setup.exe, one in Sources and one in the root of X. If you look at the manifests in a program like ResHack, you will see that the one in Sources is the one that installs Windows and not the other one.
Alternatively, you can use FactoryRecoveryTool to run any app instead of running Setup.
Man, I was so happy I got this to work!