Actually you can't (or shouldn't) have negative basis. Any losses that would cause your basis to go below zero should have been suspended since you are not at-risk.
If you did take losses in excess of your basis, the technically correct handling of this is you should pick up ordinary income to restore your basis to zero; and technically should amend the year in which this occurred.
Once your basis is determined (probably zero in your case) you now subtract your basis from any liquidating distribution. In your case all liquidating distribution would be capital gain since you have no basis. This would be reported on Schedule D and the applicable form 8949 as noted above.
*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.
