supermount or so.
Personally I use isos or cue/bin for most games. (imgmount supports multiple images)

Thanks! Using imgmount and swapping the images with ctrl-F4 worked.
I missed that feature when reading the README.

Hm any place where you'd expect it in the readme?
Maybe adding some cross-reference or so.

I think having it as a separate FAQ question immediately below "My CD-ROM doesn't work" would certainly have helped.

Maybe:
Q: How can I swap CDs while an application is running?
A: If you need to be able to switch CD during a game (or other application), you may not be able to do this using a physical CD-ROM in a CD drive, because the host operating system can lock the CD drive as long as it thinks the CD-ROM is in use.

The solution is to create images (either ISOs or CUE/BIN) of your CD-ROMs and to mount them using the imgmount command. This allows you to specify multiple images for a single virtual drive, for example:
- imgmount d /tmp/CD1.iso /tmp/CD2.iso -t iso

When the application asks you to insert the second CD, use CTRL-F4 to change from CD1 to CD2.

The same method can also be used for floppy images.

Yes, maybe merging something like that in, thanks!

If you really change the doc, it might be worth to also add some words on command line length. Can be a problem for games with more than two discs, or long paths to the images.