i guess you can do it either way a) pcmcia/ide support in kernel and use that (big!) kernel to boot from that device b) use ide<cf> adapater and smaller kernel with ide support only.
I don't think in-kernel will be enough. pcmica services depend on the card manager deamon to detect device insertions and register the device. cardmgr is user space.
So I think you will have to go early userspace or an initrd and either pivot root or kexec into another kernel.
When I did my wireless pcmcia net boot setup I had to compile the pcmcia-cs stuff against uclibc to get it small and remove the glib dependency. I was placeing it all in 1Meg of ROM so I even went further and hacked down cardmgr so that all it would do was register the device. Then I built a small initrd with all the tools. The boot system then pulled the real kernel down off the network and kexeced into it.