When I was a kid 25 years ago and didn't have money for tools, this is what I would do. It's non-destructive too. Did one just a few months ago late night, stores were closed and didn't have the tool for this freewheel. I can do all of this in about 10 minutes. It will probably take you 30 minutes.

First you need a hammer, a center punch, a rag and a towel. Sometimes there is a plastic seal that needs to be removed from the center, if there isn't one you will usually see a lockring with 2 or more dimples. Take your hammer and punch and unscrew it by going CLOCKWISE like you are tightening it. It is usually not difficult. Once it is loose there will be thin spacer rings. Keep all of that safe in a bag. Use a cloth or rag or paper towel and place it on top of the freewheel and turn the whole wheel around, over your towel, upside down. All of the cogs will come off in one or more pieces. ALL of your bearings will come loose and fall into your rag and some will fall onto your towel. Tap it while upside down to capture all of the bearings.

Now all you have left is the body that actually gets screwed to the hub with a circular spring that hold the pawls on, usually two or three. Grab one of the pawls and pull gently on it until the circular spring is loosened. Now you have your pawls loose and spring. If it is a two pawl freewheel, that is the easiest to remove. Use a LARGE adjustable wrench to loosen it counterclockwise just in the normal way of unscrewing something. It is tighter than you think. You can use a vise too. Just be careful not to damage the edges. I have never damaged one. Reassembling the freewheel is easy. Clean your disassembled freewheel and dry. Put the circle spring on and put the pawl on afterward by just sliding them under the spring. Use a dab of grease on the bearing surfaces of the cogset while upside down. Put your bearings on. With the cogset upside down and bearings stuck with the grease, take the part that screws to the hub with the pawls, in it, in your hand and hold down one of the pawls with your thumb, your middle finger in the center where the threads are for threading into the hub and put it in at an angle so that the pawl is in the cogset.

Now lower the other half in keeping your thumb on the pawl until it is gently put in place so as not to knock out the bearings. Pickup the cogset, putting pressure on the back so it doesn't come apart, put your bearings in, spacers, and finally the lockring in, the whole time keeping the whole assembly in your hand, otherwise they will separate and you will have to start over. Three pawl takes a little more effort but not much more, also more care will be needed to remove the main body from the hub because you wont have two opposing flat surfaces to clamp a wrench to. It's ready to reinstall but don't do it until you are certain you are ready for it unless you want to practice this again.