Are you swaping out the chainrings or changing the crankset completely.
If it is the crankset, you want to make sure that your old cranks and your new ones both use the same kind of bottom bracket. If it is the newer type outboard bearing bb i think all you need to do is remove the non-drive side crankarms with an allen wrench and pull it apart.
If your 53/39 is an octalink and your newer crank is the newer integrated type, you will have to buy a new bottom bracket...as well as the tools to remove the old one and install the new one.