I am large breasted and had to do this for the first couple of months. My doula called it the "Nipple Sandwich" and that's what I refer to it as now too..LOL <img src="/images/graemlins/smile.gif" alt="" />
I had to do this because I am so large--it was hard for my little one to latch on correctly so holding my hand there helped a lot. I also had to do football hold.
Remember that you may have to hold him a certain way now and help him but as he gets stronger, he WILL be able to do it correctly without help. <img src="/images/graemlins/smile.gif" alt="" />
Have you tried different positions?
The football hold and the cross-over hold are recomended for babies that have trouble opening wide enough.
Also I thought this excerpt might be of help:
"Compress the breast at the margin of the areola with your thumb and index finger, so that your hand forms a u-shape. Compressed this way, your breast should closely match the shape of your baby's mouth, so that he can take in more of the breast. Your goal is to first stimulate the baby to "root" and then to bring him onto the breast. Touch the baby's lips to your nipple until he opens wide. When he opens his mouth really wide-and not before-quickly bring him onto the breast. Do not lean toward the baby; bring his shoulders and head to you. When you pull the baby in, keep the areola compressed until he begins sucking."
from "Nursing-The First Two Months " Kathleen Huggins
Sometimes it take two months for babies to develop a good nursing routine, don't give up!