How do I use the third mouse key?

I’d like to know what patches or software I need in order to make use of my third mouse key. The mouse is a Logitech ‘Mouseman’, model ‘M-RC33’, and I am running it under Win 98. I’ve been given to understand that Win 98 does not support third keyusage on mouses (mice? meese?), but believe that there must be a workaround to this limitation. Neither the Microsoft or the Logitech sites are helpful in this regard. Will someone please help me? Thanks.