To save others from spending time trying to get this to work: I have done enough testing to safely say that connecting a CF-to-IDE adapter to the IDE ports of the original X-Surf doesn't work, in an Amiga 3000, at least.
I have tried with both IDE ports on the X-Surf, two different CF-to-IDE adapters and six CF cards. None of them are recognized in anyway, for instance by HDToolbox.
Note that the X-Surf IDE driver uses scsi.device, which the A3000's SCSI adapter also uses. But, the Commodore engineers were smart so the X-Surf IDE device is renamed to 2nd.scsi.device.
I do see the activity lights on the adapters flash during boot and when HDToolbox scans the devices.
When I connected an IDE harddisk, that worked just fine. So it's an issue with CF cards, not an issue with the hardware or drivers in general.
I have a Buddha card on the way because I want to be able to boot from a solid state drive, so for me this is not an issue, I just thought I'd write this down just in case it's useful for someone else.