I'm specially intrested in white allies that weren't leaders. I suspect they would be met with initial relucance in some places, how would they overcome this? What role did they play in both movements? Are there interesting articles that could point me to more in depth information?
Medgar Evers spoke about the white liberals who refused to act in the face of massive discrimination a lot. The whites who were involved with the SCLC and related organizations were not treated differently in his correspondence, and in fact he spoke favorably of a few allies that helped the business boycotts in Jackson in the early 60s. Given the NAACP seems the least activist organization during the time period, The impression his papers and speeches give is that there was so much action being taken and allies were so scarce anyway because of the retaliatory influence of the white citizens councils across the state that time was too short to scrutinize allies.
Source: Myrlie Evers and Medgar Evers, the autobiography of Medgar Evers