Well, if its an active bass then it kind of turns away the idea. Those harnesses are passive, made to be drop in replacements on Fender Jazz Basses. You may be able to take your bass to a local luthier or shop that has an electronics specialist and have him make a mod for you. Simply out of curiosity, what kind of bass are you using?
I think buying a Cheap P or P/J bass and modding it a little probably would be your best route. Simple fact of the matter. You cant get the P Bass sound out of a Jazz. You cant get Jazz Tone out of a P either. Just how it works.
Now I'm gonna say something thats kind on contriveral on here and I'm not sure why. If you do feel that you want to stick with just the J/J setup, don't buy the Dimarzios. Take the effort, and spend 40 extra bucks and get Sadowsky Humcancelling Jazz Pickups. The reason why this is controversal is because most people will tell you they are the same thing. Untrue. While they are based on a similar design, I find there to be a major difference in sound, leaning in Sadowsky's favor. You wont regret that descision.