What a cute little baby! I'm so sorry you couldn't leave him/her with the parents. If they are having such a hard time raising joeys, I would really consider having the male neutered and just enjoying them as pets. Do you know the parent's lineages?

Take a look at this link, it has a ton of information about hand raising joeys as well as info about incubators...

http://www.suzsugargliders.com/handraisingajoey.htm

I really really hope your little one makes it! Keep us updated!