Ok, we are transitioned to a new Mercurial repository and the code is now available again, but now requires using TortoiseAG
There is a tutorial about using TortoiseAG with Codeplex here, and the url for the mojoPortal repository you need to clone is https://hg01.codeplex.com/mojoportal
I'll be updating the documentation soon but the above link has everything you need, really you only need the first 3 steps in the tutorial.
There are some real advantages to using Mercurial repository and TortoiseAG over svn or Team Explorer, you can commit and track your own changes locally and I think with a Codeplex account you may even be able to push changes but they won't be applied and would still require someone with commit access to the server to accept the changes. I'm still learning it myself but will document it more once I get up to speed.