Hi,
I have and ipod mini 2nd gen with a CF. My advice is that at least here, not all CFs work. You need one with IDE support.
I'm using currently an A-DATA 32gb, and I've also used a RIDATA 8gb. I tried first with a Sandisk ultra II, but since it didn't have true ATA support, I was able to successfully restore using itunes, and also I saw the disk on windows, but the ipod was able to start booting, but it didn allow me to access the contents ( don remember, but I think I received a disk failure icon).
good luck!
Jose