Just stick some real Dimarzios in instead :) - I did this last weekend in my JVT-59 replacing the original "Bones" pickups that seemed to sound identical with a Dimarzio DP100 in the bridge and a Dimarzio Liquify in the neck.
Process is quite easy - just needed to unsolder the old PUPS from the circuit board under the toggle switch and solder in the new ones.
Oh and at the same time I installed a Roland GK-3 built in kit just for good measure and now having fun with the Boss GP-10 as well.