Cards are your best bet. I have bootstrapped two different business with 0% APR cards. Think hard about your household income. The higher you say it is, the better the lines will be. I'm not saying to lie, just make sure you include everything you possibly can. If your credit score is good, you should be able to get multiple cards to reach your total.
If you want a pretty sound strategy and discussion on getting a bunch of cards, check out http://www.fatwallet.com/forums/finance/ Look for the threads labelled AOR (app-o-rama).
If your 401k is in equities, I wouldn't touch it. QE3 means inflation. Plus retirement accounts are usually excluded from bankruptcy.
Ben