Yup, I replaced some last year.
Go to a building supply store and ask for a 'siding tool', here they are free. They look like an old time pop bottle opener.
You slide the end of it under the bottom edge of the siding above (yes the piece above) the piece you want to replace. When it pops, just slide the tool along the whole piece.
Now you can remove the nails from the piece you will be replacing. Then just pull it down. Cut your new piece to fit, slide into the edge and re-nail (not tight though, it needs to be able to slide a bit for expansion.
Then you have to hammer the bottom edge of the top piece you lifted with the palm of your hand to put it back in place.