I just did that about 2 weeks ago. If I had known I would have videoed it for you.
Basically you follow the same principles you would for in a house.
I tied into my bathroom drain and water lines in the basement of the rig.
If you were to follow a DIY video for house reno from Home Depot or YouTube You could get a pretty good basic idea.
Nothing sucks more than that moment during an argument when you realize you're wrong.