This is a very close copy to what california98civic has done, and I want to thank him for starting this thread. Great work!
Here's what i came up with because I couldn't find the same switch. I bought these off ebay
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They were pretty cheap. And I bought an auto gear shifter from a 96-00 civic from the junk yard pick and pull. That cost me 5 bucks.
I went to the hardware store and bought these. They're 7/8 outer diameter. They just fit inside the rubber cover of the shifter but won't fit inside the plastic main hole. I then drilled a 1/4" hole in the center of the metal washer to get the switch inside there.
I bought these 25/32" rubber gaskets in the plumbing section of Menards. They just fit inside the main hole. I drilled out a 1/4" hole for this one as well and sandwiched it between the metal washer and the body of the switch. Finally I drilled out another rubber gasket and fit it around the body of the switch behind the threads.
This assembly will just fit inside the shifter, but for added snug effect, I put a piece of electrical tape around the two rubber gaskets so I had to squeeze it into the shifter. With this friction and the fact that every time you push the button it forces the switch into the hole, I've not had it pop out yet.
I solder and heat shrink covered 2 wires to the leads and ran them down the bottom of the shifter. I wraped a little bit of electrical tape around the shift rod and just pushed the shifter over the tape. It doesn't wiggle anymore, and will turn a little bit left and right if you twist the shifter, but its pretty solid. I then ran those 2 wires to the main relay and tapped into the ground wire like california98civic did. Works like a charm. Havn't had any issues with the setup yet. I was worried the switch was too small and might not handle the amperage (not exactly sure if electricity goes through the ground wire or not), but it hasn't failed yet.
I forgot to take a picture of the assembly before I put it into the shifter, but maybe I'll pull it out and snap some pics for you guys if you're interested.
On a final note, i used bullet connectors for the switch wires and the cut ends of the ground at the main relay. If something does happen, I can always unplug the bullet connectors and then plug them back together(even on the side of the road), so it will operate like stock. Make sure one end of your cut wire is the male end, and one is the female, otherwise you'll have 2 holes or 2 sticks, and that doesn't work (electrically, "not that there's anything wrong with that" sexually.....Funny quote was that Seinfeld?).