First, I should confirm which devices use S60v1. Let me list them. I think the original Nokia N-Gage, 6610, 7650, 3650. Each of these would have their own firmware. So the user would need to know their specific model and then find the correct ROM for it.
Another angle: S60v1. S60 has multiple versions, and there's a distinction between UIQ and S60. UIQ is another platform, but S60 is Nokia's. So the user is specifically after Series 60, Version 1. So perhaps looking into old Nokia support sites. They might have had a download section for firmware, but it's no longer available. Maybe through wayback machine? Let me check that. s60v1 rom download
Another thought: the user might be looking to install a custom ROM on their S60 phone. In that case, there are custom firmware projects like NITDroid (for Android on S60), but I don't think NITDroid supports S60v1. Maybe for later versions. So perhaps the availability of custom ROMs for S60v1 is limited. First, I should confirm which devices use S60v1