Is it necessary to obtain a lawyer for a waiver/pardon? Where to begin the process?

This is very complex and if he would like to maximize his chances of approval, I would certainly recommend working with a lawyer.

Yes, you should get an attorney. Do not do this alone.

He should begin by getting an immigration attorney and can find one by contacting the Bar Association in his location or by using the "Find a Lawyer" function of this website.

I echo my colleagues' advice that your friend should definitely proceed with the assistance of an immigration attorney with waiver experience. Best of luck to your friend..

There are several key phrases and words like "caught at customs," waiver," "pardon," which would lend me to believe that the first thing your cousin should do is seek the assistance of an immigration attorney.

He may be facing grounds of inadmissibility for fraud, but we cannot be certain without first speaking with him. He should definitely contact an attorney to see if he qualifies for a waiver and the attorney will be able to better assist you after having a consultation with your cousin.