I'm not sure if Maus is referring to inking the folder before embossing or the embossed card afterwards. If it's the first, I think that's usually referred to as the Negative Embossing or negative effect. It was a TLC a good while ago, there are instructions here and the gallery link will take you to examples:
TLC160 Cuttlebug: The Negative Effect 3/17/08 by amf1066 at Splitcoaststampers. For this you can ink either side of the folder to get either an embossed or a debossed effect.
If she's referring to inking the card after embossing, when I try that I find it hard to keep the ink only on the embossed area
, even with a brayer. It gives a good look though, just different.