The easiest way to replace the shifter and shorten it is called a trick shifter (atleast thats what ive heard people call it)
Relocate the button, its only 2 wires.
Buy a shifter for a manual car, hack the shifter shaft to desired height. Cut around the plastic peice inside. Once this is done, place the knob onto the shaft, and push it down as far as it will go. The plastic peice inside is only going to allow it to go so far. however make sure the plastic peices is being pushed down. (unlocking the shifter)_ If it doesnt go down far enough to secure the knob, cut a peice off the top of the plastic until it does. Once done, secure the knob on.
You now have a trick shift, However you no longer have to push the button in to shift. So becautious when driving, not to shift it into park or reverse.
The other way, wich is basically a replacement, is to buy a Ebrake knob.
Do the same thing, however you will need to make a button to erupt out of the ebrake knob top.