You can try more liquids, but I haven't ever really done that. I just know how I feel when I drink a ton of liquids. It throws off your normal routine.
I have found that keeping things as normal as possible helps the process go faster.
If they are used to going potty in their diaper 3-4 times a day then why make them go more just so you can clean it up from the carpet? They won't be used to going that often and it could backfire and make them frustrated. Also, stick to their regular diet then they will most likely poop their regular amount too.