You do that in the external editor section of the LR Preferences.
Quote from Nik help page- Plug-ins do not appear in Lightroom after installing - Nik Collection Help
4. While Lightroom is still open, click Edit> Preferences OR Lightroom > Preferences.
5. Click on the "External Editing" tab at the top of preferences.
6. Midway down on the right click on the "Choose" button and locate the Nik Collection application file for your product. Typically it can be found at either, C:\Program Files\Google\Nik Collection\Viveza 2\Viveza 2.exe, OR Macintosh HD |Applications | Nik Collection | Viveza 2 | Viveza 2. For other products, replace Viveza 2 with the appropriate product.
7. Once located, select the program or application file as indicated above and click "Choose".
8. Set the file format to "TIFF", Color Space to sRGB (or the one of your choice), Bit Depth to 16-bit, Resolution to 240, and Compress to None.
9. Under Preset click the drop down selector and choose, "Save Current Settings as New Preset" from the list.
10. Type in the name of the plug-in such as"Viveza 2" and click Create.
You may add another plug-in by going back and following steps 6 - 10 again, otherwise close preferences by clicking OK. The plug-in(s) you added should now be accessible.
All the Nik programs (except HDR Efex Pro) can be added as external editors by this method.
Bingo! Exactly what I'm looking for.