From what I've read about Super there is no way to rollover into a 401k. I would just treat it as a separate retirement fund and when you get of preservation age (same thing as minimum age for 401k) of 55 then you can start taking distributions from it.
Here are some important differences between a 401k and Superannuation Fund:
401k is tax deferred until you start taking distibutions. It reduces your taxable income and has no money taken out of your contributions.
There is no cap on how much this fund can grow, you would just pay LT gains tax (20% in the US) on it. I don't know how the AU treat a 401k distribution, but that's something your going to ask a tax professional.
Superannuation is tax-reduced. The AU tax people take 15% on the incoming contribution. This is opposed to the 30-47% normally taken if you just took it as regular income.
There is a cap on the amounts and above that amount you lose the tax reduction. There is a limit of something like 1.1 million (and believe me if your doing this early enough and investing agressively it is possible to reach such a number). They call it Reasonable Benefit limit. Once it's above this 1.1 million the AU tax people tax it at the highest marginal rate (I think this is currently 47%). The 1.1 million number differs on whether you take as lump sum or not.
I have a 401k and will have superannuation once I start working in AU. I expect once I retire I will be getting funds from both accounts. For me this is an event at least 25-35 years from now but it's these early contributions that grow the most because of compounding and agressive investing.
I highly recommend going to
www.ato.gov.au to read up on superannuation AND consulting a tax professional so you can plan for your retirement future.
Good luck
