Note: I've tried this out on a stock RedHat 7.2 kernel (2.4.7-10) with good results, but a standard kernel 2.4.18 did _not_ work. There have been some significant changes in the usb subsystem between 2.4.7 and 2.4.18, so Enrico's driver may need some updating.
uncompress/untar it and apply this patch
tar zxf usbide-1.2.1.tar.gz
gzip -cd butterfly_patch-1.2.1.gz | patch -p0
Then, follow Enrico's excellent installation instructions to compile and install the driver.
modprobe usbide
and plug the adapter into the USB. Insert a CF card into the adapter. Check the syslog and look for messages from the driver indicating that it has detected the card. If all went well, you may create a mount point for your card in the filesystem and mount the card. After that, read and write the card as if it were an ordinary hard drive. Before ejecting the card, unmount it.
/dev/pda1 /mnt/cf auto noauto,owner 0 0
and create the mountpoint /mnt/cf. The next time you insert a Compact Flash card it should be mounted and ready to use.
Please let me know if this patch works for you.