NWDI track with JDK 1.6

Hi ,

I have built a NWDI track for EP 7.4 system and developer says need JDK 1.6 for development build.

how to define build variant to the EP 7.4 track alone

if we define JDK 1.6 to the new track, will it affect the tracks which use JDK 1.4

Do I need to install JDK 1.6 on the NWDI server?

how to avoid the conflict between JDK 1.4 and JDK 1.6 on NWDI

Please give me the exact procedure and best practice

Thanks a ton