There's always the old-school method, which is more work than a de-esser plugin but more effective and will work in situations where a conventional filtered compressor does not. I'm talking about the method in which you clone the vocal track, apply extreme filtering and compression and use that as the sidechain input to a compressor on the vocal track or bus.
KC, if you have Producer you have two bundled de-essers: the VocalStrip and the VC-64 Vintage Channel plugins. If you have the Studio edition, I think you may have to resort to third-party solutions if you want the simplicity of a de-esser plugin. The free Spitfish might work for you, although it's not entirely reliable.
A better solution would be a compressor that features a bandpass filter in the sidechain. Personally, I use FabFilter's Pro-C for most of my de-essing needs. However, a much less-expensive alternative is Klanghelm's
DC8C.