Dialogue requires an open mind.  If the racists are willing to listen to reason, then, possibly, a patient person would dialogue with them.
I remember a piece on NCR about the godson of David Duke, who, after majoring in history and talking with classmates and professors came to realize that white supremacy was wrong.
Trying to dialogue with someone whose mind is close is a waste of time.  So, those racists who are convinced of the Truth of their stance are not people with whom one can dialogue.