Setting the client setting manually is easy, just a right mouseclick on the computer, Edit settings, and add a new key/value pair.
From the client setting you need to create a property.
Assuming you have more than a fistful of computers it makes sense to automate this task.
There a several ways to get the data from cmdb into BigFix (maybe you want more information, like the responsible guy for the server, maintenance windows etc.).
- if the data is available on the server, eg. in a txt oder csv file you can create the property by using the data in the file
- Use the BigFix API: BigFix REST API Tutorial | BigFix Developer
- if the data is readable from computer name like @vk.khurava mentioned it’s also a good idea
I would strongly recommend to run intensive test, espicially for 2. on a dedicated BigFix Test server to avoid unwanted influence on production systems.