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Flame has a broadcast color spark here:
/usr/discreet/(flame version)/sparks
It's nice and simple, and other than jumping in and out of it once (it sometimes won't 'activate' unless you do that) I rarely change the default settings.
It's very harsh to illegal colors, but can be helpful for viewing contexts. in Batch, put a color corrector before the spark_broadcast node, and a difference matte after. Connect the spark_broadcast to one of the diffMatte's inputs and the color corrector to the other. Set the difference gain to soemthing high (1000 should do), and set context to it as well.
now you can color correct using the CC node and the diffMatte will show you if any illegal colors are still in your image (since the spark_broadcast node won't change anything that's not above it's limit).
generally I find dropping the saturation in the highlights has little visible effect and goes a long way to getting your colors legal.