Tracks and channels are separate things in Studio One. You can literally drag the reverb you want ducked onto the "sends" portion, and it will create an FX channel for you and send the original signal to your reverb channel. Put your compressor on there, and you're good to go!
In fact, this is even more powerful than side chaining the reverb directly, because on that channel you can put any effects chain you want. Including the splitter tool, a separate EQ for the reverb (which is almost a must) and so on.