I installed Shadow of the Comet from an original copy of the multi-lingual (DE, EN, FR, ES) CD version of the game, after experiencing two common problems, so I thought I'd post the solutions here.
I used a fresh installation of DosBox 0.74 on Windows 7 64-bit. The first problem happens if you forget to mount a C drive. Starting the install.exe from the CD then just shows an empty screen with some French text at the bottom. The fix is of course to simply mount a C drive in the DosBox, as in
mount C C:\dosbox
given that the directory dosbox exists on your Windows C drive.
The second problem happens if you mount the CD drive (letter D in my case) as
mount D D:\
Then the install.exe only shows the error message "Install path must be C:\infogram\shadow.cd" and the only options is to exit the installation. To fix this, mount the CD drive instead with the command
mount D D:\ -t cdrom -label SHADOWCD
Then the installation should work as expected 😀