You could write an output filter, using Apache::Filter, and add something like that.

But isn't fixing this at the level which it is generated in better? I mean, think of the impact this will have if you had a slight error, or if somebody changes the underlying code without updating the filter.

I would look at simply denying login/session keeping to bot useragents, or using crafty robots.txt files to simply keep them out of wherever you don't want them.

Good luck!