Here's what you'll need:
1 bar of soap
1 box of washing soda (look for it in the laundry detergent aisle at the store-it comes in an Arm & Hammer box and will have enough for six batches of detergent)
1 box of borax (this is defiantly NOT necessary but it is good for yuck-O stains)
1 5 gallon bucket
A big spoon, a measuring cup and a knife
Pour about four cups of water into a pan on your stove and turn the heat up to high until its almost boiling. While you're waiting, get your knife and start shaving strips off the bar of soap into the water whittling it down. Keep the head below a boil and keep shaving the soap. Eventually, you'll shave up the whole bar, then stir the hot water until the soap is dissolved. The water should be SUPER soapy at this point.
Put three gallon of hot water into a five gallon bucket. Mix in the hot soapy water from step on and stir for a while. Then add your cup of washing soda. Keep stirring for a minute or two and then at the borax (if you're using it). Stir for another couple of minutes and then let it sit overnight to cool.
When you wake up, the bucket should look like yucky slime...Now you are ready to do some laundry. One measuring cup (ie-1 cup) of this will be roughly what you need to do a load of laundry. So out of three gallons, you'll get about 48 loads of laundry.