Could someone provide an example on how to use QNX's mount to achieve an overlay filesystem using the "mount -o before 
after" command?

Our QNX image is on a fat32 filesystem containing the boot and image files.  This comes up as read only.  I'd like to 
overlay a writable filesystem (qnx6 for now) on top of this to ease development.  To the extent that a file created in 
the writable space would hide the file in the read-only space and be used in place of it.  For example, to achieve a 
similar result as the (typical Linux mount command using the under/over i.e. “mount -t overlay overlay -olowerdir=/
lower,upperdir=/upper,workdir=/work /merged”.)