First of all, use the scummvm provided if you want the easy way out.
Secondly, use your original discs for another easy way out, just create two bin/cue-file pairs and use this:
“Z:\>IMGMOUNT E C:\Images\MyImage1.iso C:\Images\MyImage2.iso -t iso
When mounting multiple images (useful for any application which requires discs to be swapped while it is running), you can then switch between the mounted disk-images by pressing Ctrl+F4 (by default) while your application is running.”.
Note: not tested up to disc 2!
There might be a few problems with getting the legacy version to work on dosbox, as there is CD-audio included, I used imgburn to create a bin-file of the legacy directory and then created a cue-file that had the cd-audio listed (converted to mp3, because imgburn didn’t like the original oggs).
After that you can just mount the cue as the lowest letter CD drivee (imgmount e:\t7g\t7g.cue -t iso -fs iso) and go to town.
Now, you might want to mount a secondary copy as read/write and use the installer so that you have a place for your saves, and the groovie.ini-file points to the right data directories (you can edit it), so more fiddling might be necessary.
CUE format supports data and audio tracks mixed within the same BIN image file (of course the audio is uncompressed this way). DOSBox supports audio from the BIN file as well as from external files, based on whatever the CUE specifies.
If you seem to have problems with the volume, check out the 1.3 patch (the gog version runs on 1.2!), and use alternate sound blaster drivers. I had the game set the SB-mixer volume from 100 to 6 at startup, and this maybe fixed it.
OR do what the FAQ says: set music to adlib and speech to sb.