[Freesurfer] Issue opening .dmg file for installing freesurfer patch/code addition for brainstem. Error is "image not recognized"

Hello,

I'm trying to segment the brainstem into subparts. I found online for freesurfer 5.3 you can use the following link to install the need codes:

ftp://surfer.nmr.mgh.harvard.edu/pub/dist/freesurfer/dev/

which was from the following freesurfer question/solution:

http://www.mail-archive.com/freesurfer%40nmr.mgh.harvard.edu/msg42064.html

However, when I open the ftp as a guest and try to open the .dmg file I get the error "image not recognized". Looking into why this happens it sounds like the download went bad. I've tried re-downloading the file a few times and am now wondering if the uploaded file was bad? Is there another solution so I can segment the brainstem?

Thank you for your help,

Jon