No easy way. Soak the bolts and all around the knuckle with a good rust penetrant and let it sit for 24 hours. Spray it periodically while it's sitting.

I have used longer bolts to hammer on to get the hub and bearing assembly moving without mushrooming the original 12 point bolt heads. You could use heat but it will ruin the bearing seals so plan on replacing the bearings then.

Either Snap On or Mac made a tool that would press them out when you turned the steering wheel to the full lock position but I never really had a need for it as I live in Florida.