How can I put intellectual property I create; a copyright, patent, etc. into my self-directed IRA or 401K?

I have learned that some creative investors are buying Domain Names (URLs) with 401K accounts. This method of turning a bright idea into retirement funds fascinates me-and I wonder if anyone knows the mechanics for doing the same thing with intellectual property like a copyright? Buying an existing copyrighted material with retirement account funds seems straightforward-but what about for a idea you conceive yourself? Does anyone know of a blog, forum or IRS ruling on this?