For anyone who doesn't know how to get the Color Computer 2/3 "Speech/Sound Cartridge" working, here is how I did it....
Do not use MESSUI64 1.88 because it crashes all the time when doing simple file operations
(when loading a background.png file or choosing "coco_ssc.zip" for the cart slot, etc, etc).
I'm using MESSUI64 1.87 from www.progettosnaps.net/messui/
Assuming you have the Speech/Sound Cartridge ROMs, copy "coco_ssc.zip" into your \MESS\Roms directory.
1. For this example I'll use the "Module Man" game disk. Insert the game .dsk in "Floppydisk1".
All the slots in the GUI are now empty except "Floppydisk1".
2. Start the Color Computer 2 or 3 emulation (I tested this with CoCo 3 NTSC).
3. Press [ScrlLock], [Tab], go to "Slot Devices".
For "ext" select "multi", go down to "Reset" & press [Enter].
(You now have a CoCo running the Multi-pak with FDC.)
4. Press [ScrlLock], [Tab], go to "Slot Devices".
For "ext:multi:slot3" select "ssc", go down to "Reset" & press [Enter].
Note: "ext:multi:slot4" already says "fdcv11" (Floppy Disk Controller).
(You now have a CoCo running the Multi-pack with SSC & FDC.)
5. Type LOADM"MODULE" then "EXEC". Tell the game 'Yes' the SSC is plugged in.
You will hear the guy talking at the menus and all during the game!