I've recently been doing a lot of reading and playing with calculations also. There is more than one approach for designing your cycle and for calculating macro breakdowns for each day and I think part of it is figuring out what works best for you. I'm too new to give you any advice, but here are a couple of the formulas I found...
From:
http://www.t-nation.com/free_online_..._cycling_codex
Setting nutrient intake for the "moderate days"
Protein intake should remain stable during all three types of day. At least one gram per pound of bodyweight is necessary, but I recommend 1.5g/pound of bodyweight for better results.
When trying to gain mass, the carbohydrate level on the "moderate" days should be the equivalent to the protein intake.
To lose fat, carb intake on the average days should be set at 1.25g per pound of bodyweight. For our sample guy that comes up to 275g per day.
Protein intake is kept at 1.5g/pound of bodyweight and the rest of the calories are made up with fat.
Also check the carb cycling 101 thread:
http://forum.bodybuilding.com/showthread.php?t=706139
No-Carb Day
15% of kcals from Carbs
45% of kcals from Protein
40% of kcals from fats
Low-Carb Day
30% of kcals from Carbs
45% of kcals from Protein
25% of kcals from fats
High-Carb Day
45% of kcals from Carbs
40% of kcals from Protein
15% of kcals from fats
Keep in mind the following:
1 gram of protein = 4 calories
1 gram of carbs = 4 calories
1 gram of fat = 9 calories
Hope this helps!