not certain about the back-up folder. but if you were to copy your .lg folder of the league you want to move to a flash drive, you SHOULD be able to transfer (paste) it to the new computers .lg folder for your game. never done it that way ... but should work.
what i do i make have my backup files on an external ( i save a full 2 years of game play on that external), then go to the game restore and have my external to my new computer and basically restore the game from those files, sort of a transfer but not exactly.
here's a link that explains how to make a back up and how to restore --- not meaning you don't know how, but just in case it helps ....
http://www.ootpdevelopments.com/boar...97#post4084018
best of luck. let us know how it goes and if anyone else can offer ideas, please chime in, as this isn't anything i've done before but once - so i may not be the best source.