The program works best if you follow it all together - but if you want to mix and match, you can do the exercise portion alone. However, you should not do the weights as prescribed without enough protein in your system. It might be hard to follow the WW plan and also get in your protein.
Overall, the BFL plan is a reduced calorie, lowfat plan. I think if you worked out your meals to have equal carbs and protein, that you might find you are already in the ballpark for points! Good luck!
We're fat chicks, not doctors. Please see your physician before taking advice found on the internet.