chances that you will get a virus created within the last several years to even be able to execute or even run code on 98 is about the same chance that google chrome can be installed on 9x on the topic of browsers theres none that run on 9x without needing a render proxy or heavily kernel ex that can browse the web well enough to even download a shady game from a dodgy site. so ya just download from main rig and scan it there and then transfer the files. you can try clamwin if you are that paranoid.

There's also every chance that old software has a release from an archiving group like redump, and those can be hash-checked to ensure it's the same.