Not sure about LoL 2, but Guardians of Destiny is an old dos game. All you need for that is the OSX port of
Dropbox.
I have no experience with this (so don't hold it against me if I'm wrong), but you could
probably get it off GOG, and drop the Mac binary in over the Windows doxbox executable to get it up and running. I think both use the same configuration files across all platforms, so it should be a pretty straightforward affair.
edit: Or do what guy said above me. I really should read to the end of these threads before making a reply.