Hmm... Well, this is strange. My device seems to be perfectly recognized by the system. Actually, every time I plug the phone in I get a popup window listing it under "devices and printers" with the correct model (RM-892 | Nokia Lumia 925). In the device manager it appears as a Nokia USB device, with no exclamation marks nor any sign of "wrong driver". Yet, the hacked SDK insists in not finding it.
On the other hand, I've tried to install the "winusb" driver you mention, but the link you provide redirects me to somewhere where there is no such driver, and I haven't been able to find a download. In any case, there are at least five copies of winusb.sys in my system...
Don't know what am I doing wrong.