Nero seem not to tell you that you need to download the LightScribe API from http://www.lightscribe.com/support/index.aspx?id=305. You should get a file called LS_Update_1.4.56.1_.exe which if you run, will install the missing API that goes with Nero 6 to enable the LightScribe functionality.
The download contains the actual API file called LS_HSI.msi and a copy of this is included in the bundled Nero version given away with most new LightScribe drives. Be careful though, the bundled LS_HSI.msi has been amended (possibly by Nero's developers) and will only install successfully when invoked by Nero's Setup program.
For your information, I have successfully got LightScribe to work from Nero version 6.6.0.14 onwards, although earlier versions 6.6.0.?? may also work perfectly.
Derek G