well, I am unable to locate the memstick folder in my mac, I am currently using the v1.4.2-199-g3249d8165 version of the mac built and am not being able to find the folder, as you can see in the image, this is what i have found
I'm not sure how the MAC works, but I was able to find mine on windows by opening the program, then going to file and it should have an option that mentions the memstick and it pulled mine right up directly.