Registration Points... CS3

I am loading swfs randomly into a movie target and want them to be anchored in the bottom left, so that no matter what the image size is, the corner still rests on the same point in the bottom right. What do i do? I tried to change the registration point but that had no effect… Sorry for this little query, but, as ever, it is driving me nuts.
Thanks!
Also, is anyone having trouble understanding actionscript 3.0? I am sticking with 2.0…

Thanks!
Alex