That would be a long process....
You may challenge the validity of a patent by submitting evidence of prior invention, prior art or prior publication to the USPTO. The office will conduct a reexamination of the patent and will invalidate it if it concludes that it would never had issued the patent in the first place had it known of the information you provided. If you disagree with the decision, you may appeal to the Court of Appeals for the Federal Circuit in Washington, D.C. To appeal, however, you must demonstrate that you have legal standing to file a lawsuit against the USPTO. To have legal standing means that your interests stand to be affected by the decision; for example, if you are seeking to market the patented technology and someone else owns the patent, then you probably have legal standing.