Umm...quietmorning, I think you are wrong about him needing her permission. Perhaps as a practical matter (say, getting to the Church), he needs her permission, but in NO way does he require her permission to actually receive confession, or any other sacrament. If we can have saints who have run off to monasteries without even informing their parents, then I think we can have people take part of the sacraments necessary for salvation, without permission from parents. God did put JamesR's mother as his parent, but God has also given people parents who kill them because they become Christians (such as some Muslim parents). Does that mean God doesn't want those people to join His Church? Of course not, it means that they must suffer through tense, difficult, family situations, or in some cases stop having any contact with their families. Whoever does not hate his mother and father, wife and children, his brothers and sisters, is not Christ's disciple. The day of salvation is now.
James, the following advice may be off base, and I really recommend you speak to your priest about this. However, I not long ago finished reading Wounded by Love, and it has a whole auto-biography, in a sense, of Elder Porphyrios (who many consider a saint). When he went to the Holy Mountain, he was actually younger than you are required to be to even gain entrance. However, when an older monk of the Mountain saw him on the ferry, he sat down next to Elder Porphyrios, and they spoke briefly. The older monk, who became the Elder's spiritual father, told him that when they got to the Mountain, if anyone questioned them about the boy, they would tell such a person that Elder Porphyrios was the monk's nephew. It happened to be that, for a few moments right after getting off the ferry, the monk had gotten a little ways away from the boy who would become Elder Porphyrios. An officer of the Holy Mountain's security force stopped the boy and asked him how old he was, he said the truth, and the officer was about to escort him back onto the ferry, when the monk noticed what was going on. He then came over and told the officer that the boy is with him, the officer said he is too young to be on the Mountain, and the monk told him that the boy is his nephew, and that his parents just died and so he must come to live with the monk. Through that lie, Elder Porphyrios was able to become a monk at a very young age. His spiritual father explained to him that this lie, this lie that was told out of a desire to do God's will, would be seen by God as the truth, and was therefore not truly a lie.
Again, speak to your priest, but if you would be unable to confess if your mother knew what you were going to do, misinforming her may be acceptable.