If you wanted to have a baby boy, Dr. Shettles claim that the couple should not have an intercourse 4-5 days before the ovulating period.
The position that could help perceive a baby boy is the doggy style and other related positions.
In this position the private part of the woman is too close to the cervix area so that the Y sperm travels shortly.
If a couple wanted to have a baby girl, they should hold back 2-3 days before and after the ovulation period. For the position, the couple should only have shallow penetration so that the sperm would have a longer time to travel and reach the egg cell.
These suggestions and advices are not 100% accurate, but there is nothing wrong with giving it a try.