Hello!
From your description (driver works successfully on Windows 7) I see two main possible issues, which can lead to specified behavior:
1. Some *.inf or certificate error. This issue looks easy enough to fix. Note that you must have valid certificate issued by trusted certificate authority. Self-issued certificates won't work for that.
2. You install your driver on 64-bit Windows 8, while the driver is 32-bit binary. In this case modification will much more time, but if you have compile-able sources for it, it is still possible.
In my bid I set some average value between these two choices. I can give more precise cost/time estimate if you provide some more information (driver/OS bitness, error code for unsuccessful installation etc). Ideally it would be nice to get your signed driver binaries (if it's possible) in order to try and evaluate it locally.
Best regards,
Ivan