Hello. Assuming you've figured this out by now as it's been a few months, but I'll answer in case someone else comes across this...

You need to login to your Kace appliance and download a copy of the installer .dmg by going to Settings - Agent Tokens - click your valid agent token entry, then you should see a Mac installer that you can download.

Use Composer to copy that dmg to a tmp folder on the client machine.

Then have a post installer script that mounts the dmg, runs the pkg installer, then unmounts the dmg.

Thank you for posting the solution.  It worked for Catalina as well.

I was able to extract the AMPAgent.pkg from the DMG and use a policy to deploy the package. That policy then runs a script to set the host and token information.
/Library/Application\\ Support/Quest/KACE/bin/amptools set host=server.domain token=In$ErtS3curEt0kEns7tr!|\\|gH3rE

Nice!