When I tried the game, I did not need VirtualCD imager. Make sure you lock the three CD images in macOS Sierra Finder Info panel. When mounted in SheepShaver (volumes list in SheepShaver preferences) the locked files will appear to the game software as the actual CD's.
Make sure you remove all QuickTime related files from MacOS 9.0.4 before you install the game and with it QuickTime 3. If you leave newer QT files in place the game will have sound issues: viewtopic.php?f=20&t=8525&hilit=starship+titanic#p49485