Adding glycol to a system should not require any machine or setpoint changes unless you are adding a LOT (heavy concentration) of glycol. Just consider that you will lose some heat transfer ability in both the chillers and out in the cooling coils. The chiller manufacturers print charts to calculate the loss for the concentration.
I am guessing you only want enough glycol to prevent freezing in the winter so start by figuring how low your solution temp would have to go. Then check your capacity loss to see if you can tolerate it in your system. Then fiqure how much water you have to replace in the system to get the concentration you need. Will you use the green stuff or the pink stuff?
The equip. will consume more power(chillers and pumps) to do the same work with glycol installed but there is no free lunch.
If this job goes forward let us know as there are other tips we can share with you.