I dont know, if there is posibility to calculate 95% confidence interval for (sensitivity / 1-specificity). But if you want to find the optimal cut-off point (as I understand you want) you can use Youden index (J = max[SEi + SPi - 1]) or a method, that take in to consideration the cost of a fals-positive decision and the cost of a false negative decision, that was described by Zweig in 1993
This recent paper proposes an alternative to Youden's index, and it also cites a number of papers describing methods for calculating CIs for Youden's index:
Liu X. Classification accuracy and cut point selection. Stat Med. 2012 Feb. 3.