What about writing your own script for that?
For example, prepare a few grub.conf files(i.e. grub.conf.DOS, grub.conf.linux1, grub.conf.linux2) which boot the machine into the specified OS. Then, link grub.conf to one of these files through the script file you create yourself.
But I m not sure if it works from DOS, since you cant modified files on your linux partition from DOS(or maybe you can through some utilities... I dont know...)