Having downloaded a fresh copy of WAIK, I created an iso image of CBU’s rescue disk and burnt that to a CD. Mouse and keyboard now works. The only snag is that CBU’s interface is to large for my screen. No big deal, but not quite right.
I did try the link you gave, but when trying to mount winpe (imagex /mountrw c:\winpe_x86\winpe.wim 1 c:\winpe_x86\mount) all I got was “Access denied”, despite running “Deployment Tools Prompt” as an Administrator. Thinking at first I had the wrong architecture, I tried all three variants, x86 amd64 and ia64