Transferring and problem with transcript

I want to transfer to another college. My current GPA is 2.98. However, two of my grades were not entered correctly. The school will not change them at this point.

It was suggested to me that the professors who taught me those courses could write letters explaining the situation and stating the proper grades. They did agree to do that.

With my correct grades my GPA should be ~3.4.

However, I do not know how to use those letters in order to make it work.
Shall each professor send an email to the school I’m applying to? Should the letter be mailed as a hard copy? How to ensure they will be added to my file?

I want to apply to colleges which require at least 3.0 GPA for the student to be considered for admission and fear that my applications will be rejected b/c the GPA on my official transcript will be 0.02 point below it.