As long as they do the job properly (IDE is directly compatible with CompactFlash, not SD, though reputable active converters between the latter two formats exist so chaining such a converter and an IDE-CF adapter or even finding an all in one unit isn't weird), they will work (with unofficial software, and ATAD-patched official software - not differently than using any unofficial HDD)
There will similarly be no difference in what the disk will have to contain - an APA partition "table" with PFS and HDLoader file systems (the latter of which you can manage fine when connected directly to a PC, with HDL-Dump)
In short:
- Install a MBR (note the PS2 definition of the term is different from the standard one) to the card containing wLaunchELF or older (uLaunchELF), there is a proper way to do that with HDL-Dump but it's acceptable to use a premade disk image since we'll be erasing it immediately after
- Insert it into the converter, and it into the console (always with the mechanical power switch off), it will boot directly to said homebrew
- Go to FileManager/Misc/HddManager/R1/Format to create a new and proper APA
- Use a MBR/FAT16 or 32 USB drive containing loose HDDOSD files (optional and hard to find, wink wink), and the newest FMCB installer
- If desired, copy HDDOSD files to the __sysconf and __system partitions
- Run the FMCB installer and install FHDB (required to put a proper MBR on the card, remove it afterwards if you want to)
- Done, load any homebrews/media/PS1 games using the usual filesystem-based methods (wLaunchELF + USB or RadHostClient, there's pfsshell if you really want to do it on PC but it's not too great), and PS2 backups using the greatest methods (HDL-Dump if you want to do it with the card directly connected to a PC, HDL-Dump or HDLGameInstaller (better) via ethernet, HDLGameInstaller to directly copy original or 100% backups (not recommended))
