I seem to be hearing a lot of radio commercials from folks who will show how to withdraw money from an IRA or 401(k) without a penalty as required by the IRS. How do these work?

They don't. The allowable reasons for hardship withdrawals are very few and defined clearly under tax law. Unless one meets those those criteria a penalty is involved.

In most 401Ks, you can borrow funds for virtually anything. You just have to pay it back.