It can sometimes be used positively, such as in the expression 'he has a lust for life'. However, generally you should stick with passion. It's okay to be passionate about your work, for example, but if you are lustful for your work, it sounds very weird.
When you're talking about the attraction between people, lust is seen as entirely physical, while passion is something more profound and romantic. You can lust after someone you see on the street, but you only feel passion for someone you know fairly well.