Your company will have a maximum percentage of your paycheck that can be directed to a 401K. This number is separate from the annual amount that can be deposited to either the Roth or pretax flavors of the 401K. If the percentage that the company allows is high enough, some people can make the entire year contribution in a few paychecks. Though in some case they could miss out on the entire company match.
Keeping those two limits (the per-check and the annual limit), if you are contributing pre-tax the more you contribute the less money from each paycheck will be withheld. Though the Social security and medicare number are not changed by the amount of your 401-K contributions.
To drive the withholding even lower you can bump up the the exemptions you claim via the numbers on your W-4. Upping that number will not lower your lower the Social security or medicare contribution.
As you noted if you claim enough exemptions you will lower the amount of Federal taxes withheld. The danger is that if you miss by too much, you will have a penalty to pay, plus you will have to fill out quarterly tax forms.
And that is what you must do. Each quarter you will have to make an estimate of what you are underpaying, and send additional funds to the IRS. The danger is that you must meet the deadlines, and they expect you to pay up each quarter.
Of course many people would just look into a IRA or Roth IRA after they make enough contributions to maximize the company match. Then once they know they will fill the IRA, they put additional money into their 401K.
Note: some places have a flavor of 401K that allows non-dedcutable non-Roth contributions.