What drivers did you use? I thought it'd be the MDL XHCI stack, but those aren't signed for Vista from my testing.I have now got usb3.0/3.1 working in vista boot.wim - both x64 boot.wim and x86 boot.wim . In my updated installation media - only the install.wim has been updated.
Therefore, the x64 usb3 supporting boot.wim can be used to replace the boot.wim in the updated x64 installation media
and/or the x86 usb3 boot.wim can be used to replace the boot.wim in the updated x86 installation media
If you want to install updates yourself (e.g cab files ) into running vista, you can use dism++.
If you have a lot of updates to install - do a few at a time - perhaps 50, then reboot.
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