Don't. It's prbibly against the law.
With that out of the way,it's tricky. You will need a hammer, a nail-set pin, and a very big vise (10in or more), and a rubber door mat.
Once the gun is unloaded and safe, take off the top cover, bolt, bolt carrier, gas piston, and gas tube. Thenturn it on it's back. Take the nail set pin and put it in the detent in the little rivet behing the trigger guard. Give it a good whack with the hammer. The trigger group will seperat from the barreled action. It looks very scary, but it's ok. The box mag will come out. Now, take the trigger assembly andbut it back in place. IT WILL NOT "CLICK" BACK IN PLACE YET,JUST HOLD IT THERE! Take the rubber door mat and wrap the weapon with it. Put it in the vice and GENTLY tighten it until it clicks. Now put it back together.
Get some poly mags. You will have to "fit" the mags to your gun. Lots of file work. The mags also are not all the reliable.
I have walked this road before you, my son. Do not follow this path. If thou desireith a detachable mag, gettith thee an AK.
Merry Christmas.