Well first you would need COMCTL32.ocx and then a host of other files.
I think these are all of them, just put these in your JJ3 system folder.

Most of the vehicles can be found under Inventory-Pickup-JazzItem-JazzVehicle. Note that the running shoes do not work, and do not bring up anything if you place them in a stage so I dont count them.
The car thing I think can be found under Pawn-PlayerPawn-JazzPlayer and I think is "JazzRVehicle"

Theres also a large stash of unused weapon cells like "medieval cell"(Fires arrows I think) "stone cell"(Turns anything in the aim reticle into stone, even Jazz) and "sound cell"(Pushes back enemies into the air) and more. A few are really unstable and can crash the game. These are all found under Inventory-Pickup-JazzItem-JazzWeaponCells.