Keying out multiple colors

[Mikeraphone]

Im trying to key out the skin on a particular clip to be able to smooth it using a blur layer. Anyway I know how to do it, the problem is I dont know how to key out multiple colors. I need to key out about 3 shades to get it right and can only seem to key out one. Anyone got any ideas?

[barnapkins]

just stack 3 key filters to the one layer.