There are good deals on Weatherpack style connectors and crimping tools to be found on Amazon.com as well. The trick to installing them is the crimping tool -- with a good tool it's unbelievably easy to do a professional job. Without that tool... well... not so much...
Your local mechanic probably has a tool and may make a few crimps for you if you're only going to use a few connectors and don't want to buy one. I don't know how I'd install them without it.
Don