A "rubber grommet" is a general term typically used to describe some sort of rubber ring or tube type thing.
the only rubber things you should be worried about with a CAI are the ones that connect the tubes together or connect the CAI to the throttle body and one mount that holds it to the frame rail near the headlight.
The ones that connect it to the throttle body are just large enough slip over the outside of the CAI. the mount should look like a rubber plug with a bolt through it. Only the bolt doesn't go through it. It's two bolts with the heads fastened together with an inch of rubber to allow vibration and movement of the engine in relation to the frame.