When I tell a guy "I don't need you", it is a compliment. It means "I don't need you in any way, yet I want to spend my time with you. Isn't it awesome how attractive you must be to me and how I love you so much!".
I also see it as a compliment when someone says "I don't need you" to me. It means the same: he doesn't need me, yet he wants to spend his time with me, hey damn, how cool!
To me it means that he is genuinely interested in me and has fun spending time with me, as opposed to being attached to me out of neediness.
I personally see guys who want to be needed as having a self-esteem issue. They're looking outside for the validation they lack inside.
I also think needing someone isn't healthy and that we cannot love unconditionally someone whom we need. But that's just me.
As for your question, Polyfulcrum, I don't know. Maybe you could try to explain to him that wanting him without needing him is
even better in your eyes than needing him?
Or maybe you could ask him how he feels when he feels needed by you, as opposed to when you don't need him. What does it give him exactly? Once he knows what he's looking for, maybe you two could work out a way to make him feel this way without you needing him.
Dunno. Good luck!