paul,

I am assuming you are new to this DIY project. Here are some links to help inform you on this subject:

http://www.dripdepot.com/
http://www.5min.com/Video/How-to-Install-Drip-Irrigation-with-Soaker-Dripline-130397753
http://www.ehow.com/how_5900550_install-drip-line-irrigation.html

As this info describes but may not be emphasized, you need a vacuum breaker(VB) that screws on to the faucet and then a pressure reducer that screws on to the VB before starting your poly line adapter.

There are small battery powered timers that can be inline with your system. Like any plant growing operation, you(your in-laws) must check the performance of the system out periodically that things are working properly and the plants are not drying up or drowning. It is not a hook it up, look once and forget about process. It takes time to make sure the water is enough or not enough over time. All the brands mentioned are good(although others here definitely have strong opinions on some brands). If not you will come back here and let us know. As you dig into the info don't hesitate to ask questions. GL Aloha