I always put epoxy around the pins for added support, and it could also mount that jack. I've experimented with a bunch of different ps/2 jacks and the ones that ApeShit posted have worked the best for me. Another way you could reinforce the pins is to use heat shrink tubing.

Shit yeah it works.

Wicked, my PS/2 jacks and plugs came in the mail today. Time to play stingy scientist.

Yess i think this thing can work, i have think use usb cable it have 4 "track" 2 for power and 2 for data but if you solder 4 cable of gameboy in respective points you can get usb cable link   only cons is not compatible with all gameboy, only with your mod.   Remember the view point of female pin is inverted point in male.

No no, not at all.
I mean to use the PS/2 ports in lieu of a link cable.
I don't have a link cable and they're too expensive where I live, so if I'm gonna mod in a PS/2 port for a keyboard in my Gameboy, why not make it multi-purpose and function as a link cable as well?

I added something to your picture in the OP.
Male connectors at the bottom, from the front.

EDIT:
super cool mspaint demonstration graphic

Thanks to you! i made my first prosound with your instructions , i trust in knowledge share and give the source of credit if i take from other source than me.

Mmm, you would use two keyboard at the same time?

Yeah of course, but I didn't mean have sync and kbd at the same time, I just meant having the option to use the PS/2 connector as both regular sync AND kbd.

thanx for leaving me credit in the image ;D

cool project!

Not possible. You have to choose either sync or keyboard in lsdj.

In theory, would it be possible to hook up pin 2/4 on the GB port to pin 2/6 on the mini-DIN socket and use this as a ghetto link cable, while also retaining keyboard functionality?
I've got a bunch of sockets lying around, but no link cable, and I've recently gotten a 2nd LSDj cart.

I'll probably have to solder my own cable to make sure the connections go in the right places, but it should be possible yeah?

Hot beans that's cool! Thanks for sharing.

Yes. Don't do the mod exactly like this.
Use a jack with a nut like the one Apeshit posted a pic of, so the force is applied there instead.
Or find a connector with only one jack, so the back is metal and the pins are on the bottom.
Or, if you want to fixate the jack using the current method, you could maybe put hot glue behind the jack. But then you may still have the same problem, and it's also harder to bend back the pins if there's a problem.

Thanks i try, or i try to put some resistance between connector...... if i seen the ps2 connector ready for case i'll put this

Epoxy or a glue would secure it for a while. This is why I linked to the panel mount jack, it's the best bet for something like this.