Daniel,
Just take the drums off. If that's a problem, let us know. Then, after you have taken the drums off, do as Blue advised. Take a center punch and a good size ball-peen hammer and knock them out rearwards. If you have enough stud left you may tap them out. but you must be careful to not brad them so much that they hang up in the axle.
Install new ones by inserting them from backside and draw them up into place using a breaker-bar or long-sided 4-way. Just bring them flush to the backside of the axle otherwise you may weaken them by reaching the threshold for elasticity. Stress. Good luck,
Charlie
