I couldn't tell you about AM but SotC doesn't have a life path system as far as I recall.and maybe other people more familiar with the games could correct me but I believe Spirits of the Century and Ars Magica have LP char gen.
It does have a very interesting system for creating a group of characters with established connections with each other. SotC characters start out at being highly experienced in their own field and fairly competent in a number of others. There is little to no mechanical advancement and in order to establish the characters each gets to describe two of their previous exploits in the form of "novels" they starred in. Those novels are then randomly given out to the other characters with those characters then taking on "guest star" roles in those previous exploits.
Its an interesting way of getting round the "you all meet in a bar and decide to go kill stuff" issue and it works well for the pulp genre. It doesnt hurt that SotC characters start at highly experienced.
It would be harder to translate into low level D&D if only because starting D&D characters are often just about to set out on their adventures into the world. I have used it successfully when running a high level 3.5 D&D one shot at one of my groups gaming weekends away.