It is possible to use a 5 point Likert scale in place of the 11 point Would Recommend question scale. In this case 1-3 becomes Detractors and 5 becomes Promoters. The only issue is that you lose the "0" response if you use a 5 point scale. The "0" response is considered very important in Net Promoter Score data Analysis so it's loss reduces the effectiveness of the system.