[Raion]

Currently no, emulation will not support something like this from my understanding. The ability to attach SCSI devices is moreorless limited to hard disks, and it's unlikely that MAME has any code to handle this case.

You're welcomed to try. But I would first make a new thread and maybe someone with an IRIX machine near you can dump the tapes for you and then you can return to this for science.

Not to mention, if you use an old enough machine with 32-bit windows, I don't think that you're going to get sufficient performance to make it worth your while. It could take days or hours to dump the tapes if the system has less than a fifth of the speed of a real device. That'll certainly cause damage to a very old tape drive because it probably isn't going to be able to run continuously.