It's easy to mount a Harris bipod on an AK. There's a few of different possible methods. All require removing the foregrip temporarily, and you can't have the cleaning rod on the gun with the first two methods (aka the cheap do-it-yourself methods).
Method #1: buy an Uncle Mike's machine screw swivel and get a 10/32 nut and 2 washers. Remove the foregrip retainer. You will see the hole in the bottom where the retaining screw goes. The first washer and nut go on the foregrip side of the cleaning rod hole (there's enough space for the washer to sit between the grip and the retainer, and the nut itself will sink in the cleaning rod hole). The second washer goes on the swivel, giving it surface area so it can sit on the front lip of the handguard retainer (the swivel head is too large for the groove). Quick and easy, and no permanent modifications to your gun. Downside: looks kind of ghetto.
Option #2: drill a hole in the bottom of the handguard, and tap it with an Uncle Mike's wood screw swivel. Once the hole is tapped, use a Dremel to cut off the extra length. The upside here is you get a permanent hard-mounted swivel, and only modified the foregrip. The downside is that you've put the hole straight through the cleaning rod hole, and now can't store your cleaning rod at all.
Option #3: Drill a hole at the front of the receiver, between the receiver end and front trunion, and mount your swivel there. If you cut it to the right length, you can still use the cleaning rod. This won't structurally harm your AK, and is really easy to do. It's probably one of the quickest methods. Downside: you've now got a permanent hole in your receiver.
Option #4: replace your handguard with one that has rails (such as the Tapco Fusion handguard). Get a rail-mounted bipod adapter. Attach it there. Alternatively, add a rail to the front of another handguard. Downside: the Tapco handguards generally look like crap. The Fusion looks okay, though. You can get rail covers to shield your hand for the part of the rails you don't want exposed.
I'm probably going to go for option #1 myself. I have a converted Saiga, and my AK is not set up to accept a cleaning rod; there's no place for it to screw in, and the supplied cleaning rod is longer than the barrel. Option #3 is also available because I already have a hole where the original handguard retaining screw went.
