It's actually very easy to do. I've needed to do this in the past ;-)
Open an EXS24. By default it loads a sine wave. Perfect. Trigger a C5 note or there abouts to taste as the censor bleep.
Here's a little tip if you are editing something like the voice tracks for Gordon Ramsay's Hell's Kitchen & you don't wanna automate the level of every swear word:
1. Bounce a long say 5 + second censor bleep.
2. Drag it onto a new track and mute that track.
3. Switch the Drag mode to "No Overlap".
4. Find the part you want to bleep and make a copy of the bleep and resize it to fit the part.
5. Drag it on top of the offending word(s) and resize to fit.
6. Use the crossfade tool as your secondary tool to quickly get rid of pops and clicks.