The easiest way to ask for mediation is to leave me a message on my talk page. However, please note these things:
I cannot take sides in disputes. The role of a mediator is to act as a third party, one who is neutral, to help "mediate" a discussion between two or more parties. So, please note, I cannot take sides in disputes.
I cannot make binding decisions. I have said this many times in the disputes I've mediated, we cannot make binding decisions.
Mediators discuss disputes in article content, not user conduct.
Proposal pages can sometimes be used. I have a template for these here.