I have "The 7th Guest" running successfully in DOSBox by creating CR-ROM images, and placing the following lines in the [autoexec] section:

imgmount D "C:\Classics\T7G1.iso" -t iso
imgmount E "C:\Classics\T7G2.iso" -t iso

Here's the problem: when the time comes for the game to request the second disk (the very last puzzle), it cannot access the corresponding ISO file due to the fact that it depends on its own config (groovie.ini), and there seems to be no way to reference two data locations. Here is what that section looks like:

[main]
VideoCard=VESA
midi=SoundBlasterPro2
pcm=SoundBlasterPro2
svga=on
ProgDir=C:\t7g\
DataDir=D:\t7g\
Recommended=SVGA
CPU=486dx
FreeMem=601
CDbench=300

Adding another line for a second DataDir does not work. This may be more of a T7G issue than a DOSBox issue, but I thought someone may have an idea.