How do I go about cashing in my 401k to purchase my first home.

You really need to talk to a tax advisor, cashing in or taking money out to buy a home, with all the lost interest, with all of the penalty and with the taxes to pay, this is a really poor idea.

If you withdraw (up to a certain limit) for purchase of your first home from Traditional IRA, then you don't pay early withdrawal, but withdrawal from 401K even for first home is subject to Early Withdrawal penalty. You may be able to borrow from 401K.

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Four Words: DO NOT DO IT!