I'm not sure if I completely understand your question. But here it goes...
What you're asking has nothing to do with IDE. Older laptops (Mac and PC) used IDE (as opposed to SATA) for hard drives and optical drives - but the expansion slot, if present, is on a totally different bus.
Older laptops that used PCMCIA (32-bit CardBus) slots could read CF cards provided you had a PCMCIA to CF adapter. While CompactFlash is electrically compatible with CardBus, the pin-outs are physically different.
But it's far less trouble to simply use an external USB or FireWire CF card reader instead. What's stopping you from just doing that?
I like that first one as that looks like it would be a clean installation. I've seen that third one all over ebay and always thought about getting one of those and 2x 16gb/32gb CF high speed cards but I always wondered if the OS would recognize the two cards as individuals or both together as one?
Would make for a quieter/lighter/longer lasting battery for my PB G4. 32/64gb is more than enough for my PB and would be a much cheaper approach than buying a PATA SSD.