Building speak.exe with djgpp:

1.
unzip the source with the unzip32.exe utility from djgpp.

2.
change into the src directory.
copy the makefile.dj and the speech.h file into the src directory
type in the src directory make -f makefile.dj

3.
copy the speak.exe into the main directory (cp speak.exe ..\speak.exe

Now you can use speak.exe to produce wave-files:

speak -v de -f test.txt -w test.wav

or you can produce phonemes for mbrola:

speak -v mb\mb-de4 -f test.txt >test.pho


speak --voices will list all voices.
Test it and enjoy.