How can I add a new color scheme to the heatmap?

I really like the Ylorrd color scheme, except the beige color.

I should change the beige color to the green.
Maybe I can add a new color scheme based on Ylorrd color scheme.

How can I add a new color scheme to the heatmap ?
If necessary, I am prepared to fix the source code.

Custom min color, max color was not enough to do it.