Modded quite a lot of MD2's but never taken many pictures. So here are a few....

The white mark to the left of the chip is where you cut a trace. Pin 107 is for the language select, so I lift this. 105 is the corner pin.  You can get around lifting the pin. They break easily so you might not want to lift it. It involves cutting the trace and soldering to it. It takes more time so I don't do it that way.

JP3 is for the hz setting. Red wire goes to the middle of the switch, white and black to the ends. For the language switch, green (from pin 107) goes to the middle, white and black to the ends again. (+5v and ground. I normally use white for +5v and black for ground). I used the negative side of capacitors for ground.

Now, to fit JP carts you'll need to cut these bits off the cartridge slot. I make a line on the side with a stanley knife, then cut from the top with a hacksaw and break off the piece with some pliers. You also need to sand the lower part of the sides down as simply breaking those pieces off won't allow the cartridges to fit.

I have one Japanese cartridge just to test that it fits.

...and here it is put back together.

Additional note: I don't normally put switches on the sides, but if you're using switches with an MD2 your options are limited. The last two I did, I put them on the back. Thought I'd try the side this time as I'm not keeping this so it doesn't really matter. For my own consoles I like to either have them on top at the front or I wire the console so that it's set to 60hz. I like practicality above all else, but some people like it to not look obviously modded.