There is currently no such thing available for the CPC. The only ways to use hard disks are:
- SymbOS, a Windows-95 like operatig system for the CPC, with support for the Symbiface 2 and X-Mass (both IDE based) (uses FAT)
- FutureOS, an OS with a less familiar GUI and support for the same devices (not sure which filesystem is used?)
- BonnyDOS, an expansion ROM which allows to use these same devices in AMSDOS but with a custom filesystem.
The sourcecode for any of these 3 is not available, which means the only way to get them working with other devices is: either make your device compatible with the two above, or disassemble the tools and patch the sector access routines.
Yes, RSXs are lost on ctrl-shift-esc which is why an expansion ROM is a good idea.
ACMEDOS will be the ROM you are looking for, it will allow to use the X-Mass from BASIC with the usual command and using the FAT filesystem. But his author has not published it yet, so the only thing you can do is wait for it.