|Hate to burst your bubble...|
The CF slot in the IO takes advantage of the transparent IDE mode of the CF card. In this mode (set by a certain pin being tied high or low, I believe) the CF card is electrically equivelent to the IDE bus. This means that the CF card can be connected _directly_ to the IDE bus without requiring any special circuitry. Unfortunately, I HIGHLY doubt ANY non-IDE CF card can make use of this ability. Furthermore, even if they could, the IDE (and thus CF) bus on the IO does not have any "card services" to allow the computer to detect and load drivers for devices which aren't IDE. Notice that when CF cards are not in transparent IDE mode, the pins are treated entirely differently from when they're in "bus mode".
I do not think this is possible without some additional active circuitry (which might be why there's the pads for an IC under the CF slot, I don't know). Maybe you should purchase one of those Hotswappable CF - IDE adapters and see about the specs of the chip they use...