Get your taxes done using TurboTax

go to Personal 
Other Tax Situations
Other Tax Forms
Form W-4 and Estimated Taxes - Click the Start or Update button

Say No to W4. When you get to the W4 and Estimated Taxes section, say you want to adjust your income to go though all the screens.

Or what I do is switch to Forms and open the Tax Est worksheet and play around with the settings for estimates.  You can even open each estimated form and put in the amount you want.