While it is possible to waive one's right of rescission, it is very rare, and relatively difficult. Understand two things:

a) rights of rescission were designed to protect the borrower from letting an unscrupulous lender push them into a loan they ultimately don't want. So if a borrower is electing to waive their rights of rescission, the immediate assumption is that the lender is the one pressuring them to do so. 

b) the right of rescission period lasts a grand total of 3 days--not a very long time wait for one's money. Again, is this waiver the decision of the borrower or the lender?

With these two things in mind the borrower must need a legitimate "reason" as to why they want to rescind, and they must provide a letter, drafted by them and not the lender, detailing exactly what the reasoning is. 

Qualifying reasons for a waiver would be:

• A medical emergency in which immediate money is needed
• Bond money for someone in jail
• Money needed to repair damage from a natural disaster