Never did that on a 2004 king. But if they are like the ones on my 2000 Wide Glide;

USE LOCTITE ON ALL THREADS. JUST A FEW DROPS WILL DO.

There are two pins that go through the caliper that hold the pads in place You will need a different socket to loosen them. It is a 1/4 inch with twelve points. The bolts that hold the caliper to the forks are also a 12 point but I believe it is a 10mm. So go get the right sockets.

Now that you have those odd tools, loosen but do not remove the two pins in the caliper.

Before you go farther, check the fluid level in the master. If fluid was added when the pads wore down, it will now have too much fluid and could spill on the bike when you open the calipers. It should appear a bit low right now. If not, remove some fluid so it can't spill.

Remove the two bolts that hold the entire caliper to the fork. Notice if one is longer than the other. some Harleys use a longer bolt in the top hole. Make sure they go back in the same place.

Slide the caliper off of the brake rotor. Use a tool to pry the caliper wide open. You need all the space you can get or the new pads will not slide over the rotor. If you don't have a "regular" tool for that, I have used two screw drivers or pry bars in an X pattern by pressing against the pads until all of the pistons are fully depressed.

Now you can remove the pins from the caliper. Might to pull with pliers. Pay attention to where the brake pads go. One pad has two full tabs next to the hole where the pin goes through and the other pad has one tab and one rounded off section next to the hole.

Ok now look back at how your old pads were installed in the caliper. My book is for the wide glide so it might be different. Put the new pads in the same location as your old ones were in.
If for some reason you lost track then use the next paragraph in { }.

{ If your bike has two front brakes, on the right brake caliper, the pad with two tabs installs on the inside closest to the wheel. The pad with only one full tab goes on the outside, away from the wheel.
For the left caliper, the pad with two full tabs installs on the outside furthest away from the wheel. The pad with only one tab goes on the inside closest to the wheel. }

Slip the new pads into the caliper. Install the pins by pushing in till you feel or hear a small click. You probably will have to jiggle the pads around to get the pins through but stop at the click or the pins will be too far through. Slip the caliper over the rotor and loosely install the bolts that hold the caliper to the fork.

If you have two front brakes, go to the side that has the hole through the axle. The hole should be aligned with the edge of the forks. Slip a 7/16 drill bit through that hole and make certain the bit just touches the edge of the forks. That is important for alignment of the brakes. If the drill bit does not touch the forks loosen the pinch bolt at the lowest end of the fork and slide the fork over until the drill bit touches. Tighten the pinch bolt to 30 lbs.

now tighten the bottom bolt that holds the caliper to the fork to 30lbs. then the top bolt to 30. Now you can tighten the pins that go through the caliper but be gentle, they only need 16 foot pounds of torque. That barely registers on most torque wrenches. If you have an inch pound wrench tighten to 200 inch pounds.

now you will need to pump the brake lever multiple times to get the new pads to come out and make contact with the rotor. When the brake lever feels firm that means the caliper is pinching the rotor correctly.
Check the front brake fluid reservoir and top it off if it is low.

That should do it.