Adding subtitles using Nerovision?

It is possible. You need to go into the edit movie mode, change the view to the timeline option, go up to the tabs on the upper right hand box and select the text tab, select that option for the text you want (drag it to the time line). After that you can change the text itself by double-clicking on the text box towards the top of the timeline. Here is a good tutorial (still applicable even though it is going over an earlier version):

http://www.scs.unr.edu/~ed_lab/nero.html