I was able to get an ms3pro CAN working with a canalyst-ii. Here is a rough guide on how to set it up. The device is some trickery. Fortunately, Yourdyno offers some better options for CAN integration. My goal when setting this up was to have AFR, AFR target, and ignition advance. These are very helpful to have for tuning.

First, setup the canalyst-ii. Configure both resistors. Use USB-CAN Tool to start. 

On Tunerstudio, on the top right, edit the CAN parameters. Can ID is 0.

Enable CAN Broadcasting

Edit settings for CAN Broadcasting

Edit settings for Project. I used the same configuration file for the tune. (Note that no devices are found. This was because I didn't connect in USB-CAN Tool first, when going back and making this quick guide.)

Configure on YourDyno CAN Bus. (Im having an issue with Target AFR if anyone has any ideas..)

Should get a blue light from the canalyst-ii and have live data on Yourdyno. A similar process should work for other standalone ECUs. I used components of DASH broadcasting.

Helpful links

Megasquirt CAN broadcast format
http://www.msextra.com/doc/pdf/Megasquirt_CAN_Broadcast.pdf

Yourdyno CAN video
https://youtu.be/P5y8QPqW0vg?si=zZFu_CVDoHdYPHLJ

Canalyst-ii Drivers and software
http://m.zhcxgd.com/en/