CF cards have the same pins as any other IDE interface (including 44pin 2.5" notebook drives). However, the physical size of the connectors are different, and the voltages used for the power may vary.
I don't think there's a single standard for what connector 1.8" drives use. If a CF card will physically fit the connector, then I'd bet it would work. At worst, you might fry the CF card but the laptop should be fine. Maybe you can experiment with a cheap/useless small CF card. Many digital cameras come with 16meg or similarly small CF cards--which are pretty much useless for anything other than testing whether a camera works because of the puny capacity.