@happyhappa,
from what i have learnt (only A level) for Kant, the meaning of life is all to do with becoming a good person, in yourself, not as a means to an end, if you read his principles as part of Kantian Deontology, you will see what he is getting at, also in the critique of pure reason he talks about achieving the "summum bonum" achievable only in the after life, i think it reflects Plato's Archetypes. Hope that helps somewhat, i know its a bit vague, but as i said, only A level.
Good Luck