Yeah, altirra is a fine emulator to manage MyIDE dumps.
Just dump your atari-IDE-device with a sector-editor and manage the dump with altirra.
After doing your stuff, just dump the image back and you're done
Later,
Sijmen.
P.S. This will also work with the Myide-manager.
You don't have to attach the physical disk. An image will do fine too.