Hi Janet,
In my experience, starting with why this is needed and what benefit there is to them helps to create interest and buy-in. In one organization, the coaching was more volun-told than volunteered, so I structured it as a pilot first. In that way, the value would "prove out" to the other leaders. It was also helpful that the two leaders who went into the pilot wanted to have coaches, so they brought positive attitudes and real perspectives and lessons learned on the back-end to the leadership team. If your leaders are data-driven, you could look up statistics on productivity increases, or well-being for employees, positive org culture effects, etc., on places like MIT and HBR.