I don't think that the Dropbox SDK has that level of control over files. I'm not sure that Dropbox itself is a great respecter of permissions - I've been unable to confirm exactly what it does with a quick Google search. I think you are probably going to need to script this to get the result you want.
David Masterson
Not sure, but I think that BeOrg is saving files with permission 0700 (rwx for owner) to Dropbox. I tend to use 0644 (rw for owner, r for others), but I can be convinced of other ideas. I noticed that my Org files when rsynced to Dropbox as 0644 and then read&save by BeOrg were coming back as 0700. Is what I'm seeing true? Not a big deal -- I suppose I could fix this up by my rsync script to reset the permissions on syncing down to my machine...