I am going to assume that the answer to @Anonymous_ response is "yes".
Additionally, I am going to assume that the partnership provided you with your portion of the unrecaptured section 1250 property; which is what you are attempting to enter into TT; footnote on the K-1 or other method in writing.
Finally, I am going to assume that you have computed your overall gain on the sale of your partnership interest.
If all of the above is correct, you need to enter your share of the unrecaptured section 1250 property on the Schedule D worksheet line 10.
In rereading your question, it appears that this is an override based on your facts.
If that is the case, then when you are entering the information for your final K-1, you need to indicate that this is a final K-1. At that point, TT will ask you questions regarding your selling price, tax basis and at this point I am sure that there is a question related to unrecaptured section 1250 and you would enter that information there.
TT should handle the rest.
Line 9c as noted in a response is for unrecaptured section 1250 when the partnership sells a 1250 asset.
Your unrecaptured section 1250 is the result of your sale of your interest and this is your share. Essentially what this does is taxes the gain at a 25% tax rate.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
