Step 1.  Follow the advice of TaxGuyBill and determine if it qualifies.

Step 2.  If it does in fact qualify, then go to Form 8880 and enter the info on the Line 2 Smart Worksheet as an after-tax contribution.  While that description in the smart worksheet  might not be correct, that entry will put it on Line 2 of the Form 8880, which I believe is what you are trying to accomplish.

Step 3.  Again, follow the advice of TaxGuyBill and doubly make sure if it qualifies.