How do I enter childcare expenses so I can deduct my Dependent Care FSA contributions from Box 10 in W-2 if spouse is filing separate and claiming child?

If your spouse is claiming the child as her dependent, then you cannot claim the child care credit. The child does not have to live with you to be considered your dependent, but the child does have to live with you for at least six months to get the child care credit. 

Thanks for the response, but that did not answer my question. I understand I cannot receive the credit. I am asking about deducting dependent care expenses via my Dependent Care FSA.

According to this Turbo Tax link "Taxpayers using the Married Filing Separately status do not qualify for the dependent care credit. In addition, funds put into an FSA for dependent care are already "pre-tax". This means you've already received a tax benefit for these amounts. Therefore, no additional credit or deduction would be allowed for the same amount."