So I have done some digging in to this and I believe the issue in question is not so much related to the firewire device itself but rather the connected device and what it believes it should be talking to drivers wise. The IEEE 1394 device itself should not need any device drivers directly as its supported by the operating system in native drivers, but from what I understand a change made by Microsoft in Windows 8 removed some legacy files that older devices were reliant on and while newer devices work fine the older devices ceased to function due to the loss of these drivers from the OS.
This is briefed outlined at the following link
As you noted the links for this package appear to be dead. However I have tracked down this software package for you and it can be acquired at the following location now.
As for using this package in Windows 10, while this may be possible it does carry some other issues. Firstly this package will deploy a set of drivers in to the Program Files Folder ( or Program Files x86 folder on Windows 64Bit ) So these are the legacy driver files for the OHCI Device. However they are for Windows 8 and as such are digitally signed for Windows 8. They are not signed for Windows 10 and while I have read that people have used them with success in Windows 10 it may require some additional steps to bypass driver signing enforcement so you can force the firewire adaptor to use these drivers instead of the OS Native ones and get them to run at boot time to support devices that are required to use these specific legacy drivers. You can find articles online on this topic
Obviously we do not recommend bypassing driver signature enforcement, as it has its purpose in protecting boot time drivers and plays a part in system security, I appreciate however to get your older device to continue to function it may be a necessary requirement to do so if you wish to also upgrade to Windows 10. This would appear to be the only solution to this issue as its unlikely an official fix for Windows 10 will ever come because it would have done so by now I think if it was ever going to.
Hopefully this information is what you were after. While I cannot say for sure it will work for you, it does appear to have assisted others to get various legacy firewire devices working in Windows 10 so should you choose to go ahead and try it, I do hope this works for you as well.