Choosing baby's sex, is it possible

Hi,
I want to know if the theory of choosing gender by having certaing kind of diet and having sex 3-4 days before ovulation ( for girl) and 1 day before ovulation ( for boy) really works..

How much does the diet affect it all, We really want to have a son so I am willing to go on just about any kind of diet if it helps us achieve this.

I need to know what diet will help me conceive a boy and also how will I know what is the right time of the month or day for me and my husband to lock ourselves in the bedroom.