No - you
cannot, as they are being reported
via Form W-2, as a deduction from your income. All you
have to do is report W-2 data in Turbo Tax exactly as it appears on the form.
Since
you do not report the amount of the deposit as taxable income on your income
tax, it effectively works like a tax deduction. If your employer makes
matching or other additional deposits to your account, those are also
tax-deferred and there's no need for any additional reporting.