Use heat and a soft metal punch/drift. Put the hub/disk in the oven to warm it up, . it will make it easier to get the race out. If you use a piece of aluminum or brass as a drift and support the hub so the race can pop out you can go ahead and wail away as hard as you can with a big hammer and work around the edge, it will come out. If you use a steel drift (like a screw driver or something) you run a high risk of screwing up the hub. I highly recomend the free race installer tool from autozone (other chain stores probably have similar)for pounding the new ones in, it does a great job and makes it very easy. Just make sure to keep your hub and races clean. Also be sure to get a good high melting point grease, mobile one or better. having recently been stranded by a failed bearing I would recomend replacing the races while you are at it, if you can find the above mentioned tools (heat, soft metal drift, race tool) you can definitally get it done. Good luck!