Go through the same process to update your stack, and you can set:
DVR_SHARE=C:\CHANNELS_DVR
To get your LOGS_SHARE value (which is where the CDVR executable resides), you can use the OliveTin Action for generating a filtered log, and search for:
This will tell you what path Channels used to startup, and you want that path -- minus the last data
part. In other words LOGS_SHARE should be set to this value:
PORTAINER_HOST is the IP address or hostname (if it resolves correctly) of the system where Portainer is running. Sounds like for you, localhost would work, though you could also use the LAN IP address of that system.
You'll also want to generate your PORTAINER_TOKEN, so that you can use Project One-Click. This is done by using the dropdown in the upper right corner of Portainer, next to your username, followed by selecting "My account". Create an Access Token named OliveTin, and use it for your PORTAINER_TOKEN value. Be aware you'll only be able view it once, so store it somewhere secure, for potential future use.