Contact HR dept or company managing your 401k ask about penalties associated with drawing out 401k. Most charge 15% interest as you saved without paying interest, then 10% penalty (their maybe is a loophole being a home).They will send you papers takes about 2 weeks.
Cashing out a 401(k) before the retirement age results in severe tax penalties. Depending on your situation you may be able to make this up with homebuyer tax credits.
It is not advised that you cash out your 401K at any time till you reach retirement, even to add in purchasing a home. When you cash out a 401k you are penalized to a point that makes it not worth it, you are also taxed heavely on the funds you remove.