For something simple, you can simply rename the demos to the numbers they will be in the menu.
So on your floppy you would have the following:
S (directory)
startup-sequence (inside S)
1 (demo renamed to 1)
2
3
Then edit the startup sequence to something like:
echo " "
echo " My fantastic startup menu"
echo " "
echo " "
echo " Type the number of your selection:"
echo ""
echo "1 - Spaceballs"
echo "2 - CNCD"
echo "3 - etc."
echo ""
Not fancy tho...