Upon accessing the file within Drive, you can go into menu, then file, and finally choose "save as, " which gives you the ability to save directly to your device (Dropbox and Skydrive are also included as options as well, though this can be done even faster by choosing the "send" feature).
Substitute files need to retain the name of the file they replace, and swapped games remain mislabeled in the Neo Geo X menu, but the trick has already allowed some users to install the popular AES Unibios.