That sounds like the Stanley Burroughs,
LEMON DRINK for Master Cleanse
Here's a copy of it I happen to have on my puter
You'll need:
2 TBsp lemon or lime juice (approx. 1/2 lemon)
2 TBsp genuine organic maple syrup, Grade B (the darker the better)((This is for vitamins)
1/10 Tsp cayenne pepper, gradually increase (the more BTUs the better)((many health benefits))
10-14 oz pure water (Water must be chlorine free, fluoride free, pollutions free)

Combine juice, maple syrup, and cayenne pepper with water. Drink every 1 to 2 hours. Take no other food, but do drink lots of water in between lemonade drinks.

Use fresh lemons or limes only, never canned or frozen lemon juice. Use organic and vine ripened when possible. Also, Mix your lemonade fresh just before drinking. Don't mix it up in the morning for the whole day. You can, however, squeeze your lemons in the morning and measure out the 2 TBsp when needed.

Burroughs recommends a minimum of 10 days on this. You can do 40 days safely and more.

This actually is supposed to be done in conjunction with salt water flushes every morning.

I have never done this as a fast. But I was using the drinks as a type of cleanse about three times a day along with eating light. I think they taste great. In the info I have he suggests breaking out of the fast gradually day by day.

From what I've heard it's supposed to be an excellent cleansing fast.