Honestly, I am not sure if there is much a difference in the amount of ALA needed. I do know that if you want to lose more fat than the more ALA the better to a certain extent. Bulking..... Use whatever you feel comfortable with.... Fonz once had a ratio of saying without ALA and you gain 20 pounds, 10 pounds may be muscle while the other 10 will be fat.
With ala it is possible to gain 20 pounds but have 14 pounds be muscle and 6 pounds be fat. This is not a standard number but just is an example of the difference ALA can do while bulking. I don't see why taking 3 grams of ALA while bulking will hurt.... it may not let you gain as much weight because it will slow fat depositing but it will ensure that more of the gains are muscle.
Like stated before, start at 1500mgs ED and find out what works best for you.