In this picture you can see the wool before dyeing on the bottom right. The chelsea rolls arrayed out on top of it, and to the left is an echo I placed on top of the wool in the pan with natural wool to show the colours of dye I used on each one. Though the beginning colour is not eggplant you can achieve similar interesting variances.
The best dyeing advice I can give you is just go for it, you can't really go wrong. If it seems implausible, you should really try it. Like I said to Christine today, this idea , to go for broke is what separates the men from the boys.