If I were you, I would read three blog posts that Tara Walker made about developing Windows 8, starting with this: Overview, Installation, and MonoGame 3.0.
The third blog post talks about creating a Content Console outside of Mono Game (using XNA) and importing it into your MonoGame project. It looks like you will need XNA, so you will need to read its information and figure out how to make it work in VS2012 Express.
I was engaged in the MonoGame project in my free time, and I managed to load some textures and sprite lists without a special content project; everything is simply added to the project solution and created during the initialization of the main class. But I do not know if this will be viable in the long run.
NTN.
markp3rry
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