Nice work. You've done a very neat job of it. Not to my taste to be honest, but if you like it that's all that matters.
vinceherman, Lady Luck was with me this time around and I did not have to extend any wiring. I was prepared to, and bought wires from gauge 18 to 26 but did not have to use it.
First remove the left grip. Mine is heated and therefore has a cable but it is pretty long. Lift up a little rubber tab (on the side next to the Mode switch) and you will find 2 tiny Phillip screws diagonally opposed. After removing them, it slides out.
To open the control next to this grip, just remove the two screws all the way and the wires will keep it together and allow you to work with it nicely. Or you can do it the same way the throttle as described next.
For the throttle assembly, you loosen the two screws about 1/4 inch each or more, and spread the half apart (these are security torx (star) screws) slowly until it rotates on the handlebar.
I first opened it completely and had a bit of hard time putting it together because the return spring for the throttle is quite strong and kind of tricky to put together but I managed.
I recommend buying a kit with the security torx if not done already as this will be show stopper when you get there.
Next, the kill switch/cruise control assembly: You can remove the 2 screws all the way and remove it. No reason to try and keep the back end of the assembly attached to the front.
Then, the mirror on the left, a piece of cake to remove and the front brake lever assembly, nothing tricky here either.
Before you start, make sure you have all the tools (metric of course) to remove all bolts/screws and nuts, i.e. in these parts, including a socket to remove the banjo at both ends of the upper brake line (both same size).
Allen wrench for the mirror and brake lever assembly and a socket (or wrench to hold the 2 nuts holding the mirror clamp together).
You also need to remove the "tank" the headlight, the bar supporting the 2 turn lights, the console (don't worry, only four screws and there is nothing to it).
Now, Zero wisely have used wiring quite long and have tucked the unused cable behind the headlamp and sometimes routed the wires around things in there to take up the slack, so you must unplug like 6 or 7 connectors but they are all different, so no worries there.
What I found is that no tools are needed to unplug them: Just examine the connector carefully and you'll see the spot where you need to press to release the clip on the other end that will allow you to just pull them apart (while you press the clip).
Now, if you are not going to go all the way up like I did and will be using a shorter handlebar, you might not need to "free up" all the wiring and it might be easier to do the mod. You have to play it by ear and see what your particular situation requires.
The blinkers are wired kind of strange and not really color coded, I recommend attaching a piece of color tape to the wires if it becomes necessary in your setup to remove them from the bike while you re-route all the cables.
The last thing to mention is the holes you'll need to drill on the new bar, you must copy the location from the original to the new bar, both in distance from the bars' ends and the relative position to the top of the bar, (or the front or back)
They were made with metric bits but I don't think you'd have any issues if you use standard bits and choose the next size up. Except for the two holes that will need thread for the left grip. These are 4 MM thread if you want to reuse the original screws but realistically, you can switch to standard screws (countersink head) if you only have standard taps. They will be size 6 or maybe 8.
The other 3 holes don't need thread and are just to ensure the controls don't slip around the bar if the screws become a bit loose.
I know it sounds very complicated at times but it is not: I am just not a good explainer and once you get going it will be obvious what to do next.
The good news is you can always abort and put it back together the way it was, since you are not modifying any control cables or any other crucial part.
You'll need to get some extra DOT 4 brake fluid to recharge the system after draining it to replace the line. I drained mine at the front caliper, on the right side.
Don't forget to have a few new copper washers available as re-using the old ones is a recipe for leaks.
Any more questions? Just ask. Sorry about the long post but better to have too much detail than too little.