Fantastico: adb worked first time and bin4ry's script did too.
This is what was different between my attempt and the kit you posted:
1) The driver .dll files in the SDK I downloaded from google seem to be a more recent version (1009 instead of 1007 and around 40% bigger)
2) The following three lines in android_winusb.inf: I'd just blindly copied the values shown in Windows device management and omitted the third line completely:
; Scroll Evoke (comment line)
%SingleAdbInterface% = USB_Install, USB\VID_2207&PID_0010
%CompositeAdbInterface% = USB_Install, USB\VID_2207&PID_0010&MI_01
%SingleBootLoaderInterface% = USB_Install, USB\VID_2207&PID_0010
As far as the .android folder goes, it appeared to be already in order.
Thank you so much and I hope this helps anyone else who is struggling.