Maintaining an Elgg session across sub domains

I have seen a lot of people ask this question on the web and here in the community, but I have yet to find a solid answer. I am trying to maintain one elgg session accross multiple subdomains such as: and

With other applications and sites I've built, this solution has helped, but it does not work with Elgg.

I am assuming Elgg is setting the session cookie in a way that I need to modify. Any ideas or help? Thanks in advance.