Windows 98 may use the Fat16 file system so you MAY have a problem. (It might not be able to write to your flash drive in lehmans terms) I know little about Mac's.
1. Look for flashdrive in "my computer"
2. Download roster to desktop.
3. unzip downloaded file to flash drive. (using winzip or whatever you chose)
do you know if its windows98 or windows 98SE? if just 98, you have little usb drive support. (so it ends there) My understanding is that not many external drives work on 98.
sorry i couldnt help more.
:note: you can use USB devices on win98 but usually requires some drivers and/or bios changes. Too much stuff to walk through here.