I believe I am experiencing something similar. I have the 2012 Mini with the Fusion Drive and 10.8.2, and am trying to install Windows 7.
In the initial Windows installation steps, I can see the BOOTCAMP partition, but when I try and install Windows on it, Windows says something like it can't find a system partition.
Since it can see the partition, it doesn't seem like a storage driver issue, but I'm wondering whether there is something about the Fusion drive that is preventing Windows 7 from installing.
I was able to install Windows 8 on this Mini previously, so it seems that Windows 7 is missing something that is required to install on the Fusion Drive.
I am having the same problmes this very minute. I am bringing in another batch of Windows support s/w from Apple and am going to try again but for the last few attempts I am stuck at the "drivers" issue. I have no idea what drivers Win7 is looking for. Same machine as yours. Funny thing, I just set the Mrs. up with a 32 bit Win7 and it was a breeze to install and get up and running on an iMac from 2009. Go figure. I will be watching this thread. If you have progress, please post. Thanks.
Here's what I did and it worked. When the Win installer comes to the panel with all the drive partitions and when you click on the BootCamp partition and it does nothing, look to the lower right and there should be a selection there that says "more" or "other" or something like that. Click on that and there will appear more selections to chose from. One says "Format" go ahead and format your BootCamp partition then all of a sudden the installer will take off and follow through with the installation and six hours later from the time your began your Windows mission, you can be right here posting while in Win7. Just like me.
Well, the first time I did format the BootCamp partition with Win 7, just like I did for the Win 8 install previously, and I still got the error.
But I just tried again after a reboot, and the Win 7 install worked this time.
But the partitions listed were different this time. Previously Windows displayed partitions on 2 disks (disk 1 and disk 2), but this time it only displayed one disk. So something changed between the first time I tried it and this second time.
After the failure the first time, I read some discussions on the Fusion drive, and it appears that the Boot Camp partition is created on the mechanical drive only, and that if you use Boot Camp / Windows, you will not gain any benefit from the SSD or Fusion architecture. If this is accurate, it is a bummer.