I have been use both OneNote and the "Projects as Contacts" in Outlook methodology for awhile. I wanted some way to use OneNote for my larger projects, to gather reference materials, take notes during meeting, etc. and link them back to my Project in Outlook.
Turned out to be easier than I thought - create a subfolder in your "My Notebook" directory called "Projects". Then in OneNote create new sections in that subdirectory.
Since each section is a separate ".one" file, it is eay in Outlook to Insert a new Item as a shortcut to that particulate project ".one" file.