craftgrrl | Leather dye

I kind of forgot I was a member of this community, sorry.

I've got a pair of leather boots I want to dye. I usually use Lady Esquire which is very good, but they don't have the colour I want (dark green) (or any kind of green, or I'd just mix). Dylon has an even smaller selection of colours, so my question is this:

What is leather dye? I know fabric dye is watered down emulsion (take note), someone must know what leather dye is? Acrylic? Plasticote?

I don't want to experiment myself as these boots were PRICEY.

Thanks.