I have, with the help of a support request, been able to figure this out for Logic. Thanks Niclas!
Here is my walkthrough.
Create a new instrument but opt for the 5 mono (I didn't care about the other options so I haven't tried to configure them). Set your output to "bus 1."
This is not a multi-timbal instrument so you probably don't want to check that box. I have no need for the library to be opened either so I uncheck that too.
When Logic has created the track, press the "X" key on your keyboard to view your mixer. If you have a custom setup, that may be done differently for you.
When the mixer is visible, you'll see your pianoteq track that you'll then see a + in the bottom right corner of the channel fader. Click it four times (it won't let you do more than that because it only has 5 out) to add your discreet microphone channels.
After this, you'll want to rename the "Aux 1" to something considerably easier to manage. I rename mine to "Piano Sum."
After you have renamed the summing channel, you can then select all of the added channels, but not the first one, and not the sum, only the pianoteq channels 2, 3, 4, and 5. With all of them selected, pick the "output," dropdown and choose "Bus 1 > Piano Sum." All four should automatically update to send their audio to the "Piano Sum," channel strip.
You're done with the mixer but you can click on the pianoteq instance to open the plug-in window from here. This is where I open the plugin window from. In the pianoteq window, you'll see a microphone next to something that says, "sound recording," or any number of other options. On that bar, click the microphone to open the routing window.
With the routing window open, you'll see a grid. That grid confused me a bit because I didn't realize that each row is a different output and each column is a different microphone. In this area you could route microphone 1 to output 5, but you might find that confusing if you want to work on the project at a a later date. I tend to set microphone 1 to output one. You'll have values in each of the columns already. I set each microphone to 0db in the row that matches the microphone and everything else to nothing. Make sure the microphone is also "on," because if it's greyed out, you won't get a signal either.
How you end up configuring your setup, and why you might want to do this is entirely up to you. I'm really happy that I can play with different microphones, different placements, and different everything. I can put a huge wide open delay effect on channel five but leave one and two panned hard left and right, with their microphones at each end of the piano to get a really sweet sounding "intimate," but still big sound. I'm still new to microphone techniques but this will give me (and anyone else) a means of playing with their sound stage without having to have an actual sound stage to play with.
I am not quite dialed in on how the delay within he output matrix works, or why I'd want to modify it so you can see that I left the values that were already there in my walkthrough. I suspect it has something to do with phase issues and actually making the sound stage "real." Your mileage may vary.
Other creative effects could be employed that would have your primary piano sound untouched, but with one of the remaining three channels completely modulated, distorted, or mangled in some way. The possibilities are endless. The ability to mix them in for a very specific sound is awesome.
I hope this helps someone.
Thanks for reading.