Voice warning instead of sound

I am using an HP2410 with Tom Tom 3. I have downloaded Speed Cameras etc and have set the warnings on the overlay screen however i have since tried to replace the basic sound warning with a voice but don't seem to be able to do it. It just keeps coming up with the "Tom Tom wizard discover" sound. Any ideas???
DAC

hiya DAC, I saved them (.wav files) to 'My Documents' on PDA, opened CheckPOInt overlays and found the one I wanted to use in 'My Documents' and enabled it in CheckPOInt.