Q: When booting my iMac 27" Retina 5K device to install Windows 7 the kb and mouse are unresponsive in the Windows install screens.  The boot device is a USB 2 flash drive.

Thanks for not giving up on me Loner T!

I did check hosts file - no apple entry is present there. I believe this is how it should be?

I am busy creating flash drive with win 8.1 - I will update about the results once I attempt installation.

Finally some good news! Win 8.1 installed fine! Apparently it has some driver missing in win7... don't know...

Well not all is great - when installing bootcamp drivers I got the message: "This version of Bootcamp is not intended for this computer model"

I have some devices not installed -  the network adapter and wireless are among them unfortunately.

Loner T, the drivers you have, are they going to work on win8.1?

Else I will try searching for the proper drivers one by one...

I expect unknown devices, if you use .5621.

My testing was done using a iMac5K and W8.1 64-bit in Oct-Nov 2014. They should work. Boot Camp on iMac Retina 5K? is the thread on which I had posted my results.

Here is the link to the .dmg - https://www.dropbox.com/s/div1yevpn105alt/WindowsSupport.dmg?dl=0 . You need to unpack the DMG or restore it to a USB2 Flash drive. Open the Bootcamp.xml file and verify that the version is correct. (.5766). Let me know if you need the md5 for the DMG.

Thank you, I am downloading it now - I am not quite sure how to unpack the DMG or restore it to a Flash drive, but I'll ask google I'll keep you posted of the results.

I wonder, once installed, how do I update those drivers (if apple releases updates)... Windows update?

The DMG can be restored to a USB2 stick using Disk Utility. Please see Disk Utility (Yosemite): Restore a disk image to a disk .

Loner T - thank you thank you thank you!!!

All worked well - no unknown devices in device manager now!

Only that I couldn't restore the .dmg, I unpacked it and copied it on a USB2.0 drive (as you suggested).

Thanks once again for helping me end this saga!

It took me almost 3 days to install windows! Hands down - this is my longest installation ever!

In the end it was worthed - I am new to MAC OS - now I feel bit more confident!

Excellent. . Please make backups of OSX and Windows.

I will!