Asansa, The Lotus Position, Impossible? Options

Have been sitting in asana for a good few yers now, basically corss legged and yet after all this time I still can't manage to sit properly for more than a few minutes. Can basically do a 1/4 lotus, not a full half, leg on upper thigh but its fustrating. Sat comfortably the other day and realized that its the essence to a good practice, all that shifting and shuffling during the MP or general meditation just dosen't cut it... throws everythnig off. Main thing I'm trying for now is a full lotus, a stable position that keeps the back straight and energy flowing for an undisclosed period of time.

Can anyone here do the full lotus? How did you achive it and how long did it take?

Peace
.M.

Hello,
I have a question about this... I'm also trying to achieve stillness with an asana, but I have scoliosis, not that critical (i think) but if you pay atention to my back It's posible to spot it. And when I try to sit with my back straight, I often find it hard to have the neck and the back aligned (and i also feel the shoulders are at diferent heights). Anyone had this problem o knew of someone who did? How did you solve it?
I really want to overcome this problem, since I can't meditate lying in the floor because i fall asleep.
Thanks in advance
Saquian