After rereading you above posts: Dont know why the cd command fails, please paste the complete output. Is the folder existing at all?
Try installing the games to your rootfs and then move the stuff manually to MyDocs and create a symlink to the stuff in the former place. You also have to set mount options for MyDocs to be executable, but i do not know exactly [Fumbling with permissions inside linux on fat32 file system is not a good idea in my opinion].