Is the dust cap the rubber thing under the boot that goes around the shifter? If so my car already has one so why wouldn't yours?
Anyway from what I have seen you...
jack the car up
Go under and un bolt the shifter from the linkage
Go pull the old shifter from up top (if you leave the knob on it should work).
Drop the new shifter in
Bolt it to the linkage
Done, I guess.