Overriding the built-in flash

I have a friend with a 40D.

He asked me earlier today why he can't take a photo (in conjunction with the built-in pop-up flash) at speeds higher than his sync-speed. He actually wants to take a photo with a black bar visible (long story).

It's been a while since I owned a 40D and I just couldn't remember whether there was indeed a way round this. Everytime he selects a fast shutter speed, the camera corrects him and goes back to the sync-speed.

Any suggestions?

I dont think there is with the built in flash.

I don't believe that pop-up flashes on any Canon camera have enough energy to do high-speed shutter sync. Certainly the pop-up on my new 60D does not support it. However, both the 430EX II and 580EX II do support high-speed sync if either is mounted in the hot shoe.