Clearly the federal tax credit has expired, but our state has a slightly different kind of tax credit, which is about $10,000 payable over three years. The buyer must be a first-timer and must live in the home. Unfortunately for your situation, in order to get the credit, all persons on title must be first time homebuyers (no home in their name for at least three years), so if you own your current home you could not be on title on her home if she wants to get the credit.
And if you are not on title, many lenders will not accept your cosigning. The reason for this is that you personally would have little to lose if you didn't make the payments, while someone who lives in the home has more to lose and it makes the loan a bit more secure. Sit down with a reputable lender and review their requirements to see if it is feasible. I admire your wanting you help your child get a head start in homeownership, but it may be very difficult to also get the tax credit.
Good luck to you!