another dyeing question

I had success with the curtains but now I need to know about dyeing a carpet. It is too light, a faint aqua, and needs to be a deeper green. I know this can be done, because my mother-in-law did one years ago, that wouldn't come clean with a carpet shampooer. So she dyed it a dark blue. Does anyone know how to do this? I thought about the possibility of actually putting the dye in the shampooer.....